diff --git a/accounts/doctype/sales_invoice/sales_invoice.js b/accounts/doctype/sales_invoice/sales_invoice.js
index 345dbc9..d8d06dd 100644
--- a/accounts/doctype/sales_invoice/sales_invoice.js
+++ b/accounts/doctype/sales_invoice/sales_invoice.js
@@ -93,12 +93,18 @@
 					wn.model.map_current_doc({
 						method: "stock.doctype.delivery_note.delivery_note.make_sales_invoice",
 						source_doctype: "Delivery Note",
-						get_query_filters: {
-							docstatus: 1,
-							customer: cur_frm.doc.customer || undefined,
-							company: cur_frm.doc.company
+						get_query: function() {
+							var filters = {
+								docstatus: 1,
+								company: cur_frm.doc.company
+							};
+							if(cur_frm.doc.customer) filters["customer"] = cur_frm.doc.customer;
+							return {
+								query: "controllers.queries.get_delivery_notes_to_be_billed",
+								filters: filters
+							};
 						}
-					})
+					});
 				});
 				
 			// cur_frm.add_custom_button(wn._("POS View"), function() {
diff --git a/accounts/doctype/sales_invoice/sales_invoice.py b/accounts/doctype/sales_invoice/sales_invoice.py
index ca93786..09df5f6 100644
--- a/accounts/doctype/sales_invoice/sales_invoice.py
+++ b/accounts/doctype/sales_invoice/sales_invoice.py
@@ -1001,10 +1001,12 @@
 		bean = webnotes.bean(target)
 		bean.run_method("onload_post_render")
 		
-	def update_item(obj, target, source_parent):
-		target.amount = (flt(obj.qty) - flt(obj.delivered_qty)) * flt(obj.basic_rate)
-		target.export_amount = (flt(obj.qty) - flt(obj.delivered_qty)) * flt(obj.export_rate)
-		target.qty = flt(obj.qty) - flt(obj.delivered_qty)
+	def update_item(source_doc, target_doc, source_parent):
+		target_doc.amount = (flt(source_doc.qty) - flt(source_doc.delivered_qty)) * \
+			flt(source_doc.basic_rate)
+		target_doc.export_amount = (flt(source_doc.qty) - flt(source_doc.delivered_qty)) * \
+			flt(source_doc.export_rate)
+		target_doc.qty = flt(source_doc.qty) - flt(source_doc.delivered_qty)
 	
 	doclist = get_mapped_doclist("Sales Invoice", source_name, 	{
 		"Sales Invoice": {
diff --git a/controllers/accounts_controller.py b/controllers/accounts_controller.py
index 725fdb3..3d72e6f 100644
--- a/controllers/accounts_controller.py
+++ b/controllers/accounts_controller.py
@@ -394,7 +394,6 @@
 				
 				total_billed_amt = flt(flt(already_billed) + flt(item.fields[based_on]), 
 					self.precision(based_on, item))
-				webnotes.errprint([max_allowed_amt, total_billed_amt])
 				
 				if max_allowed_amt and total_billed_amt - max_allowed_amt > 0.02:
 					webnotes.msgprint(_("Row ")+ cstr(item.idx) + ": " + cstr(item.item_code) + 
diff --git a/controllers/queries.py b/controllers/queries.py
index caa2f6f..462c22d 100644
--- a/controllers/queries.py
+++ b/controllers/queries.py
@@ -23,7 +23,7 @@
 			filters = filters.items()
 			flt = []
 			for f in filters:
-				if f[1][0] == '!':
+				if isinstance(f[1], basestring) and f[1][0] == '!':
 					flt.append([doctype, f[0], '!=', f[1][1:]])
 				else:
 					flt.append([doctype, f[0], '=', f[1]])
@@ -204,4 +204,20 @@
 		and `%s` like %s order by ref_currency asc limit %s, %s""" %
 		("%s", "%s", searchfield, "%s", "%s", "%s"), 
 		(filters["price_list_name"], filters['buying_or_selling'], "%%%s%%" % txt, 
-			start, page_len))
\ No newline at end of file
+			start, page_len))
+			
+def get_delivery_notes_to_be_billed(doctype, txt, searchfield, start, page_len, filters):
+	return webnotes.conn.sql("""select `tabDelivery Note`.name, `tabDelivery Note`.customer_name
+		from `tabDelivery Note` 
+		where `tabDelivery Note`.`%(key)s` like %(txt)s %(fcond)s and
+			(ifnull((select sum(qty) from `tabDelivery Note Item` where 
+					`tabDelivery Note Item`.parent=`tabDelivery Note`.name), 0) >
+				ifnull((select sum(qty) from `tabSales Invoice Item` where 
+					`tabSales Invoice Item`.delivery_note=`tabDelivery Note`.name), 0))
+			%(mcond)s order by `tabDelivery Note`.`%(key)s` asc
+			limit %(start)s, %(page_len)s""" % {
+				"key": searchfield,
+				"fcond": get_filters_cond(doctype, filters, []),
+				"mcond": get_match_cond(doctype),
+				"start": "%(start)s", "page_len": "%(page_len)s", "txt": "%(txt)s"
+			}, { "start": start, "page_len": page_len, "txt": ("%%%s%%" % txt) }, debug=True)
\ No newline at end of file
diff --git a/public/js/transaction.js b/public/js/transaction.js
index 2cee843..4a647ad 100644
--- a/public/js/transaction.js
+++ b/public/js/transaction.js
@@ -75,8 +75,10 @@
 	
 	company: function() {
 		if(this.frm.doc.company && this.frm.fields_dict.currency) {
-			var company_currency = this.get_company_currency();
-			this.frm.set_value("currency", company_currency);
+			if(!this.frm.doc.currency) {
+				this.frm.set_value("currency", this.get_company_currency());
+			}
+			
 			this.frm.script_manager.trigger("currency");
 		}
 	},
diff --git a/stock/doctype/delivery_note/delivery_note.py b/stock/doctype/delivery_note/delivery_note.py
index 81c4b6c..25a70b6 100644
--- a/stock/doctype/delivery_note/delivery_note.py
+++ b/stock/doctype/delivery_note/delivery_note.py
@@ -369,11 +369,37 @@
 			from accounts.general_ledger import make_gl_entries
 			make_gl_entries(gl_entries, cancel=(self.doc.docstatus == 2))
 
+def get_invoiced_qty_map(delivery_note):
+	"""returns a map: {dn_detail: invoiced_qty}"""
+	invoiced_qty_map = {}
+	
+	for dn_detail, qty in webnotes.conn.sql("""select dn_detail, qty from `tabSales Invoice Item`
+		where delivery_note=%s and docstatus=1""", delivery_note):
+			if not invoiced_qty_map.get(dn_detail):
+				invoiced_qty_map[dn_detail] = 0
+			invoiced_qty_map[dn_detail] += qty
+	
+	return invoiced_qty_map
+
 @webnotes.whitelist()
 def make_sales_invoice(source_name, target_doclist=None):
+	invoiced_qty_map = get_invoiced_qty_map(source_name)
+	
 	def update_accounts(source, target):
 		si = webnotes.bean(target)
 		si.run_method("onload_post_render")
+		
+		si.set_doclist(si.doclist.get({"parentfield": ["!=", "entries"]}) +
+			si.doclist.get({"parentfield": "entries", "qty": [">", 0]}))
+		
+		if len(si.doclist.get({"parentfield": "entries"})) == 0:
+			webnotes.msgprint(_("Hey! All these items have already been invoiced."),
+				raise_exception=True)
+				
+		return si.doclist
+		
+	def update_item(source_doc, target_doc, source_parent):
+		target_doc.qty = source_doc.qty - invoiced_qty_map.get(source_doc.name, 0)
 	
 	doclist = get_mapped_doclist("Delivery Note", source_name, 	{
 		"Delivery Note": {
@@ -391,6 +417,7 @@
 				"prevdoc_docname": "sales_order", 
 				"serial_no": "serial_no"
 			},
+			"postprocess": update_item
 		}, 
 		"Sales Taxes and Charges": {
 			"doctype": "Sales Taxes and Charges",