diff --git a/erpnext/patches/patch.py b/erpnext/patches/patch.py
index 5dd8b8d..9a82945 100644
--- a/erpnext/patches/patch.py
+++ b/erpnext/patches/patch.py
@@ -345,7 +345,7 @@
 		for b in bin:
 			bobj = get_obj('Bin',b[0])
 			prev_sle = bobj.get_prev_sle(posting_date = '2011-09-01', posting_time = '01:00')
-			bobj.update_item_valuation(posting_date = '2011-09-01', posting_time = '01:00', prev_sle = prev_sle)
+			bobj.update_entries_after(posting_date = '2011-09-01', posting_time = '01:00', prev_sle = prev_sle)
 	elif patch_no == 368:
 		from webnotes.utils import nestedset
 		t = [
diff --git a/erpnext/stock/doctype/bin/bin.py b/erpnext/stock/doctype/bin/bin.py
index 13c0fee..d1cf65e 100644
--- a/erpnext/stock/doctype/bin/bin.py
+++ b/erpnext/stock/doctype/bin/bin.py
@@ -1,18 +1,11 @@
 # Please edit this list and import only required elements
 import webnotes
 
-from webnotes.utils import add_days, add_months, add_years, cint, cstr, date_diff, default_fields, flt, fmt_money, formatdate, generate_hash, getTraceback, get_defaults, get_first_day, get_last_day, getdate, has_common, month_name, now, nowdate, replace_newlines, sendmail, set_default, str_esc_quote, user_format, validate_email_add
-from webnotes.model import db_exists
-from webnotes.model.doc import Document, addchild, removechild, getchildren, make_autoname, SuperDocType
-from webnotes.model.doclist import getlist, copy_doclist
-from webnotes.model.code import get_obj, get_server_obj, run_server_obj, updatedb, check_syntax
-from webnotes import session, form, is_testing, msgprint, errprint
+from webnotes.utils import cint, cstr, flt
+from webnotes.model.code import get_obj
+from webnotes import msgprint
 
-set = webnotes.conn.set
 sql = webnotes.conn.sql
-get_value = webnotes.conn.get_value
-in_transaction = webnotes.conn.in_transaction
-convert_to_lists = webnotes.conn.convert_to_lists
 
 # -----------------------------------------------------------------------------------------
 
@@ -45,13 +38,7 @@
 			if serial_no:
 				self.check_qty_with_serial_no()
 			
-			prev_sle = self.get_prev_sle(dt, posting_time, sle_id)
-			cqty = flt(prev_sle.get('bin_aqat', 0))
-			# Block if actual qty becomes negative
-			if (flt(cqty) + flt(actual_qty)) < 0 and flt(actual_qty) < 0 and is_cancelled == 'No':
-				msgprint('Not enough quantity (requested: %s, current: %s) for Item <b>%s</b> in Warehouse <b>%s</b> as on %s %s' % (flt(actual_qty), flt(cqty), self.doc.item_code, self.doc.warehouse, dt, posting_time), raise_exception = 1)
-
-			self.update_item_valuation(sle_id, dt, posting_time, serial_no, prev_sle)
+			self.update_entries_after(dt, posting_time)
 
 	def check_qty_with_serial_no(self):
 		"""
@@ -81,33 +68,22 @@
 		""", (self.doc.item_code, self.doc.warehouse), as_dict=1)
 		return sle and sle[0] or None
 
-	# --------------------------------
-	# get previous stock ledger entry
-	# --------------------------------
-			
-	def get_prev_sle(self, posting_date, posting_time, sle_id = ''):
-		# this function will only be called for a live entry
-		# for which the "name" will be the latest (even for the same timestamp)
-		# and even for a back-dated entry
-		# hence there cannot be any "backdated entries" with a name greater than the
-		# current one
-		
-		# if there are multiple entries on this timestamp, then the last one will be with
-		# the last "name"		
-		# else, the last entry will be the highest name at the previous timestamp
-		# hence, the double sort on timestamp and name should be sufficient condition
-		# to get the last sle
+	def get_prev_sle(self, posting_date = '0000-00-00', posting_time = '00:00'):
+		"""get previous stock ledger entry"""
+		# get the last sle before the current time-bucket, so that all values
+		# are reposted from the current time-bucket onwards.
+		# this is necessary because at the time of cancellation, there may be
+		# entries between the cancelled entries in the same time-bucket
 
 		sle = sql("""
 			select * from `tabStock Ledger Entry`
 			where item_code = %s
 			and warehouse = %s
-			and name != %s
 			and ifnull(is_cancelled, 'No') = 'No'
-			and timestamp(posting_date, posting_time) <= timestamp(%s, %s)
+			and timestamp(posting_date, posting_time) < timestamp(%s, %s)
 			order by timestamp(posting_date, posting_time) desc, name desc
 			limit 1
-		""", (self.doc.item_code, self.doc.warehouse, sle_id, posting_date, posting_time), as_dict=1)
+		""", (self.doc.item_code, self.doc.warehouse, posting_date, posting_time), as_dict=1)
 
 		return sle and sle[0] or {}
 
@@ -121,11 +97,13 @@
 		diff = cqty + s['actual_qty']
 		if  diff < 0 and (abs(diff) > 0.0001) and s['is_cancelled'] != 'Yes':
 			msgprint("""
+				Negative stock error: 
 				Cannot complete this transaction because stock will 
-				become negative (%s) in future transaction for Item 
-				<b>%s</b> in Warehouse <b>%s</b> on <b>%s %s</b>""" % \
+				become negative (%s) for Item <b>%s</b> in Warehouse 
+				<b>%s</b> on <b>%s %s</b> in Transaction %s %s""" % \
 				(str(diff), self.doc.item_code, self.doc.warehouse,
-					s['posting_date'], s['posting_time']), raise_exception=1)
+					s['posting_date'], s['posting_time'], s['voucher_type'], s['voucher_no']), \
+					raise_exception=1)
 
 	# ------------------------------------
 	# get serialized inventory values
@@ -222,11 +200,14 @@
 			stock_val = sum([flt(d[0])*flt(d[1]) for d in self.fcfs_bal])
 		return stock_val
 
-	# ----------------------
-	# update item valuation
-	# ----------------------
-	def update_item_valuation(self, sle_id=None, posting_date=None, posting_time=None, serial_no=None, prev_sle=None):
-		# no sle given, start from the first one (for repost)
+	def update_entries_after(self, posting_date, posting_time):
+		"""update item valution from the give stock ledger entry (sle)
+		   onwards."""
+		
+		# Get prev sle
+		prev_sle = self.get_prev_sle(posting_date, posting_time)
+		
+		# if no prev sle, start from the first one (for repost)
 		if not prev_sle:
 			cqty, cval, val_rate, self.fcfs_bal = 0, 0, 0, []
 		
@@ -237,11 +218,11 @@
 			val_rate = flt(prev_sle.get('valuation_rate', 0))
 			self.fcfs_bal = eval(prev_sle.get('fcfs_stack', '[]') or '[]')
 
-		val_method = get_obj('Valuation Control').get_valuation_method(self.doc.item_code)	# get valuation method
+		# get valuation method
+		val_method = get_obj('Valuation Control').get_valuation_method(self.doc.item_code)
 
 		# recalculate the balances for all stock ledger entries
-		# after this one (so that the corrected balance will reflect
-		# correctly in all entries after this one)
+		# after the prev sle
 		sll = sql("""
 			select *
 			from `tabStock Ledger Entry` 
@@ -250,30 +231,32 @@
 			and ifnull(is_cancelled, 'No') = 'No'
 			and timestamp(posting_date, posting_time) > timestamp(%s, %s)
 			order by timestamp(posting_date, posting_time) asc, name asc""", \
-				(self.doc.item_code, self.doc.warehouse, posting_date, posting_time), as_dict = 1)
+				(self.doc.item_code, self.doc.warehouse, \
+					prev_sle.get('posting_date','0000-00-00'), prev_sle.get('posting_time', '00:00')), as_dict = 1)
 
-		# if in live entry - update the values of the current sle
-		if sle_id:
-			sll = sql("select * from `tabStock Ledger Entry` where name=%s and ifnull(is_cancelled, 'No') = 'No'", sle_id, as_dict=1) + sll
-		for s in sll:
+		for sle in sll:
 			# block if stock level goes negative on any date
-			self.validate_negative_stock(cqty, s)
+			self.validate_negative_stock(cqty, sle)
 
-			stock_val, in_rate = 0, s['incoming_rate'] # IN
-			serial_nos = s["serial_no"] and ("'"+"', '".join(cstr(s["serial_no"]).split('\n')) + "'") or ''
+			stock_val, in_rate = 0, sle['incoming_rate'] # IN
+			serial_nos = sle["serial_no"] and ("'"+"', '".join(cstr(sle["serial_no"]).split('\n')) \
+				+ "'") or ''
 
 			# Get valuation rate
-			val_rate, stock_val = self.get_valuation_rate(val_method, serial_nos, val_rate, in_rate, stock_val, cqty, s) 
+			val_rate, stock_val = self.get_valuation_rate(val_method, serial_nos, \
+				val_rate, in_rate, stock_val, cqty, s) 
 			
 			# Qty upto the sle
-			cqty += s['actual_qty'] 
+			cqty += sle['actual_qty'] 
 
 			# Stock Value upto the sle
 			stock_val = self.get_stock_value(val_method, cqty, stock_val, serial_nos) 
-			# update current sle --> will it be good to update incoming rate in sle for outgoing stock entry?????
+			
+			# update current sle --> will it be good to update incoming rate in sle 
+			# for outgoing stock entry?????
 			sql("""update `tabStock Ledger Entry` 
 			set bin_aqat=%s, valuation_rate=%s, fcfs_stack=%s, stock_value=%s 
-			where name=%s""", (cqty, flt(val_rate), cstr(self.fcfs_bal), stock_val, s['name']))
+			where name=%s""", (cqty, flt(val_rate), cstr(self.fcfs_bal), stock_val, sle['name']))
 		
 		# update the bin
 		if sll:
diff --git a/erpnext/stock/doctype/landed_cost_wizard/landed_cost_wizard.py b/erpnext/stock/doctype/landed_cost_wizard/landed_cost_wizard.py
index 58ba751..e1d5774 100644
--- a/erpnext/stock/doctype/landed_cost_wizard/landed_cost_wizard.py
+++ b/erpnext/stock/doctype/landed_cost_wizard/landed_cost_wizard.py
@@ -86,9 +86,9 @@
 						d.save()
 					sql("update `tabStock Ledger Entry` set incoming_rate = '%s' where voucher_detail_no = '%s'"%(flt(d.valuation_rate), d.name))
 
-					bin_name = sql("select t1.name, t2.name, t2.posting_date, t2.posting_time from `tabBin` t1, `tabStock Ledger Entry` t2 where t2.voucher_detail_no = '%s' and t2.item_code = t1.item_code and t2.warehouse = t1.warehouse LIMIT 1"%(d.name))
+					bin_name = sql("select t1.name, t2.posting_date, t2.posting_time from `tabBin` t1, `tabStock Ledger Entry` t2 where t2.voucher_detail_no = '%s' and t2.item_code = t1.item_code and t2.warehouse = t1.warehouse LIMIT 1"%(d.name))
 					if bin_name and bin_name[0][0]:
-						obj = get_obj('Bin', bin_name[0][0]).update_item_valuation(bin_name[0][1], bin_name[0][2], bin_name[0][3])
+						obj = get_obj('Bin', bin_name[0][0]).update_entries_after(bin_name[0][1], bin_name[0][2])
 
 		# now distribute the taxes among the PRs
 		for lc in getlist(self.doclist, 'landed_cost_details'):
@@ -140,11 +140,11 @@
 						d.valuation_rate = (flt(d.purchase_rate) + (flt(d.rm_supp_cost) / flt(d.qty)) + (flt(d.item_tax_amount)/flt(d.qty))) / flt(d.conversion_factor)
 						d.save()
 					sql("update `tabStock Ledger Entry` set incoming_rate = '%s' where voucher_detail_no = '%s'"%(flt(d.valuation_rate), d.name))
-					bin_name = sql("select t1.name, t2.name, t2.posting_date, t2.posting_time from `tabBin` t1, `tabStock Ledger Entry` t2 where t2.voucher_detail_no = '%s' and t2.item_code = t1.item_code and t2.warehouse = t1.warehouse LIMIT 1"%(d.name))
+					bin_name = sql("select t1.name, t2.posting_date, t2.posting_time from `tabBin` t1, `tabStock Ledger Entry` t2 where t2.voucher_detail_no = '%s' and t2.item_code = t1.item_code and t2.warehouse = t1.warehouse LIMIT 1"%(d.name))
 
 					# update valuation of the item
 					if bin_name and bin_name[0][0]:
-						obj = get_obj('Bin', bin_name[0][0]).update_item_valuation(bin_name[0][1], bin_name[0][2], bin_name[0][3])
+						obj = get_obj('Bin', bin_name[0][0]).update_entries_after(bin_name[0][1], bin_name[0][2])
 
 	def add_deduct_taxes(self, ocd, oc, tax_amount, total_amount, total, prev_total, f=1):
 		ocd[oc].total_amount = flt(tax_amount.toFixed(2))		 
diff --git a/erpnext/stock/doctype/stock_reconciliation/stock_reconciliation.py b/erpnext/stock/doctype/stock_reconciliation/stock_reconciliation.py
index f040df3..e133d6f 100644
--- a/erpnext/stock/doctype/stock_reconciliation/stock_reconciliation.py
+++ b/erpnext/stock/doctype/stock_reconciliation/stock_reconciliation.py
@@ -131,18 +131,18 @@
 			update item valuation in previous date and also on post date if no qty diff
 		"""
 		
-		self.update_item_valuation_pre_date(d)
+		self.update_entries_pre_date(d)
 		
 		if not flt(d[self.label['qty']]) and not flt(d[self.label['actual_qty']]):
 			# seems like a special condition when there is no actual quanitity but there is a rate, may be only for setting a rate!
 			self.make_sl_entry(1,d,1)
 			self.make_sl_entry(1,d,-1)
 		elif not qty_diff:
-			self.update_item_valuation_post_date(d)
+			self.update_entries_post_date(d)
 				
 	# update valuation rate as csv file in all sle before reconciliation date
 	# ------------------------------------------------------------------------
-	def update_item_valuation_pre_date(self, d):
+	def update_entries_pre_date(self, d):
 		mar = flt(d[self.label['mar']])		
 
 		# previous sle
@@ -168,15 +168,12 @@
 				
 	# Update item valuation in all sle after the reconcliation date
 	# ---------------------------------------------------------
-	def update_item_valuation_post_date(self, d):
+	def update_entries_post_date(self, d):
 		bin = sql("select name from `tabBin` where item_code = '%s' and warehouse = '%s'" % (d[self.label['item_code']], d[self.label['warehouse']]))
 		bin_obj = get_obj('Bin', bin[0][0])
 
-		# prev sle
-		prev_sle = bin_obj.get_prev_sle(self.doc.reconciliation_date,self.doc.reconciliation_time)
-
 		# update valuation in sle posted after reconciliation datetime
-		bin_obj.update_item_valuation(posting_date = self.doc.reconciliation_date, posting_time = self.doc.reconciliation_time, prev_sle = prev_sle)
+		bin_obj.update_entries_after(posting_date = self.doc.reconciliation_date, posting_time = self.doc.reconciliation_time)
 
 	# --------------
 	# make sl entry
diff --git a/erpnext/stock/doctype/stock_uom_replace_utility/stock_uom_replace_utility.py b/erpnext/stock/doctype/stock_uom_replace_utility/stock_uom_replace_utility.py
index f8ac737..0fa7a3b 100644
--- a/erpnext/stock/doctype/stock_uom_replace_utility/stock_uom_replace_utility.py
+++ b/erpnext/stock/doctype/stock_uom_replace_utility/stock_uom_replace_utility.py
@@ -85,7 +85,7 @@
       for w in wh:
         bin = sql("select name from `tabBin` where item_code = '%s' and warehouse = '%s'" % (self.doc.item_code, w[0])) 
         if bin and bin[0][0]:
-          get_obj("Bin", bin[0][0]).update_item_valuation(sle_id = '', posting_date = '', posting_time = '')
+          get_obj("Bin", bin[0][0]).update_entries_after(posting_date = '', posting_time = '')
 
     # acknowledge user
     msgprint("Item Valuation Updated Successfully.")
diff --git a/erpnext/stock/doctype/warehouse/warehouse.py b/erpnext/stock/doctype/warehouse/warehouse.py
index f3d600d..7384c19 100644
--- a/erpnext/stock/doctype/warehouse/warehouse.py
+++ b/erpnext/stock/doctype/warehouse/warehouse.py
@@ -68,7 +68,7 @@
     bl = sql("select name from tabBin where warehouse=%s", self.doc.name)
     for b in bl:
       bobj = get_obj('Bin',b[0])
-      bobj.update_item_valuation(posting_date = '2000-01-01', posting_time = '12:00')
+      bobj.update_entries_after(posting_date = '2000-01-01', posting_time = '12:00')
 
       sql("COMMIT")
       sql("START TRANSACTION")
diff --git a/erpnext/utilities/doctype/reposting_tool/reposting_tool.py b/erpnext/utilities/doctype/reposting_tool/reposting_tool.py
index c4f021b..489a3b6 100644
--- a/erpnext/utilities/doctype/reposting_tool/reposting_tool.py
+++ b/erpnext/utilities/doctype/reposting_tool/reposting_tool.py
@@ -88,7 +88,7 @@
 		bin_act_qty =	flt(bin_obj.doc.actual_qty)
 		try:
 			# udpate actual qty and item valuation
-			bin_obj.update_item_valuation('', '2000-01-01', '00:00')
+			bin_obj.update_entries_after('0000-00-00', '00:00')
 			# get bin qty
 			qty_dict = self.get_bin_qty(bin_obj.doc.warehouse, bin_obj.doc.item_code)