minor fixes in sales invoice validation
diff --git a/erpnext/controllers/accounts_controller.py b/erpnext/controllers/accounts_controller.py
index 683f72b..1f2e3b2 100644
--- a/erpnext/controllers/accounts_controller.py
+++ b/erpnext/controllers/accounts_controller.py
@@ -415,7 +415,7 @@
 
 					if total_billed_amt - max_allowed_amt > 0.01:
 						reduce_by = total_billed_amt - max_allowed_amt
-						frappe.throw(_("Cannot overbill for Item {0} in row {0} more than {1}. To allow overbilling, please set in 'Setup' > 'Global Defaults'").format(item.item_code, item.row, max_allowed_amt))
+						frappe.throw(_("Cannot overbill for Item {0} in row {0} more than {1}. To allow overbilling, please set in 'Setup' > 'Global Defaults'").format(item.item_code, item.idx, max_allowed_amt))
 
 	def get_company_default(self, fieldname):
 		from erpnext.accounts.utils import get_company_default