diff --git a/application/controllers/items.php b/application/controllers/items.php
index 515d67c0d..c9ef537b5 100644
--- a/application/controllers/items.php
+++ b/application/controllers/items.php
@@ -617,9 +617,9 @@ class Items extends Secure_area implements iData_controller
 		if ($this->Item->get_item_id($item_number) != FALSE)
 		{
 			$this->form_validation->set_message('item_number_check', $this->lang->line('items_item_number_exists'));
-			echo json_encode(array('success'=>true,'message'=>$this->lang->line('items_successful_adding'));
+			echo json_encode(array('success'=>false,'message'=>$this->lang->line('items_error_adding')));
 		}
-		echo json_encode(array('success'=>false,'message'=>$this->lang->line('items_error_adding'));
+		echo json_encode(array('success'=>true,'message'=>$this->lang->line('items_successful_adding')));
 	}
     
 }
diff --git a/application/controllers/receivings.php b/application/controllers/receivings.php
index 2c32b3d5c..047487ddb 100644
--- a/application/controllers/receivings.php
+++ b/application/controllers/receivings.php
@@ -193,18 +193,26 @@ class Receivings extends Secure_area
 			$data['supplier']=$suppl_info->first_name.' '.$suppl_info->last_name;
 		}
 		$invoice_number=$this->_substitute_invoice_number($suppl_info);
-		$data['invoice_number']=$invoice_number;
-		$data['payment_type']=$this->input->post('payment_type');
-		//SAVE receiving to database
-		$data['receiving_id']='RECV '.$this->Receiving->save($data['cart'], $supplier_id,$employee_id,$comment,$payment_type,$data['stock_location'],$invoice_number);
-		
-		if ($data['receiving_id'] == 'RECV -1')
+		if ($this->Receiving->invoice_number_exists($invoice_number))
 		{
-			$data['error_message'] = $this->lang->line('receivings_transaction_failed');
+			$data['error']=$this->lang->line('recvs_invoice_number_constraint');
+			$this->_reload($data);
+		}
+		else
+		{
+			$data['invoice_number']=$invoice_number;
+			$data['payment_type']=$this->input->post('payment_type');
+			//SAVE receiving to database
+			$data['receiving_id']='RECV '.$this->Receiving->save($data['cart'], $supplier_id,$employee_id,$comment,$payment_type,$data['stock_location'],$invoice_number);
+			
+			if ($data['receiving_id'] == 'RECV -1')
+			{
+				$data['error_message'] = $this->lang->line('receivings_transaction_failed');
+			}
+	
+			$this->load->view("receivings/receipt",$data);
+			$this->receiving_lib->clear_all();
 		}
-
-		$this->load->view("receivings/receipt",$data);
-		$this->receiving_lib->clear_all();
 		$this->_remove_duplicate_cookies();
 	}
 	
@@ -356,6 +364,14 @@ class Receivings extends Secure_area
     	$this->receiving_lib->clear_all();
     	$this->_reload();
     }
+    
+    function check_invoice_number()
+    {
+		$receiving_id=$this->input->post('receiving_id');
+		$invoice_number=$this->input->post('invoice_number');
+		$exists=!empty($invoice_number) && $this->Receiving->invoice_number_exists($invoice_number,$receiving_id);
+    	echo json_encode(array('success'=>!$exists,'message'=>$this->lang->line('recvs_invoice_number_duplicate')));
+    }
 
 }
 ?>
\ No newline at end of file
diff --git a/application/controllers/secure_area.php b/application/controllers/secure_area.php
index 3a05865bc..dff0bf988 100644
--- a/application/controllers/secure_area.php
+++ b/application/controllers/secure_area.php
@@ -24,6 +24,7 @@ class Secure_area extends CI_Controller
 		$logged_in_employee_info=$this->Employee->get_logged_in_employee_info();
 		$data['allowed_modules']=$this->Module->get_allowed_modules($logged_in_employee_info->person_id);
 		$data['user_info']=$logged_in_employee_info;
+		$data['controller_name']=$module_id;
 		$this->load->vars($data);
 	}
 	
diff --git a/application/language/en/receivings_lang.php b/application/language/en/receivings_lang.php
index 24edd1cdc..0babf19b8 100644
--- a/application/language/en/receivings_lang.php
+++ b/application/language/en/receivings_lang.php
@@ -55,4 +55,5 @@ $lang['recvs_receipt']='Receivings Receipt';
 $lang['recvs_date_required']='A correct date needs to be filled in';
 $lang['recvs_date_type']='Date field is required';
 $lang['recvs_delete_confirmation'] = 'Are you sure you want to delete this receiving, this action cannot be undone';
-?>
+$lang['recvs_invoice_number_duplicate'] = 'Please enter an unique invoice number';
+?>
\ No newline at end of file
diff --git a/application/models/receiving.php b/application/models/receiving.php
index 65996ea5b..e44db43a4 100644
--- a/application/models/receiving.php
+++ b/application/models/receiving.php
@@ -168,6 +168,18 @@ class Receiving extends CI_Model
 		return $this->Supplier->get_info($this->db->get()->row()->supplier_id);
 	}
 	
+	function invoice_number_exists($invoice_number,$receiving_id='')
+	{
+		$this->db->from('receivings');
+		$this->db->where('invoice_number', $invoice_number);
+		if (!empty($receiving_id))
+		{
+			$this->db->where('receiving_id !=', $receiving_id);
+		}
+		$query=$this->db->get();
+		return ($query->num_rows()==1);
+	}
+	
 	//We create a temp table that allows us to do easy report/receiving queries
 	public function create_receivings_items_temp_table()
 	{
diff --git a/application/views/receivings/form.php b/application/views/receivings/form.php
index 92abbd1b2..0570c2ccf 100755
--- a/application/views/receivings/form.php
+++ b/application/views/receivings/form.php
@@ -74,6 +74,24 @@
 
 $(document).ready(function()
 {	
+	$.validator.addMethod("invoice_number", function(value, element) 
+	{
+		var id = $("input[name='receiving_id']").val();
+
+		return JSON.parse($.ajax(
+		{
+			  type: 'POST',
+			  url: '<?php echo site_url($controller_name . "/check_invoice_number")?>',
+			  data: {'receiving_id' : id, 'invoice_number' : $(element).val() },
+			  success: function(response) 
+			  {
+				  success=response.success;
+			  },
+			  async:false,
+			    dataType: 'json'
+        }).response).success;
+    }, '<?php echo $this->lang->line("recvs_invoice_number_duplicate"); ?>');
+	
 	$('#date').datePicker({startDate: '<?php echo date("%Y/%M/%d");?>'});
 	$("#recvs_delete_form").submit(function()
 	{
@@ -83,7 +101,8 @@ $(document).ready(function()
 		}
 	});
 	
-	var format_item = function(row) {
+	var format_item = function(row) 
+	{
     	var result = [row[0], "|", row[1]].join("");
     	// if more than one occurence
     	if (row[2] > 1 && row[3] && row[3].toString().trim()) {
@@ -92,7 +111,8 @@ $(document).ready(function()
     	}
 		return result;
 	};
-	var autocompleter = $("#supplier_id").autocomplete('<?php echo site_url("receivings/supplier_search"); ?>', {
+	var autocompleter = $("#supplier_id").autocomplete('<?php echo site_url("receivings/supplier_search"); ?>', 
+	{
     	minChars:0,
     	delay:15, 
     	max:100,
@@ -102,7 +122,8 @@ $(document).ready(function()
     });
 
 	// declare submitHandler as an object.. will be reused
-	var submit_form = function(selected_supplier) { 
+	var submit_form = function(selected_supplier) 
+	{ 
 		$(this).ajaxSubmit({
 			success:function(response)
 			{
@@ -110,13 +131,14 @@ $(document).ready(function()
 				post_form_submit(response);
 			},
 			error: function(jqXHR, textStatus, errorThrown) {
-				selected_customer && autocompleter.val(selected_supplier);
+				selected_supplier && autocompleter.val(selected_supplier);
 				post_form_submit({message: errorThrown});
 			},
 			dataType:'json'
 		});
 	};
-	$('#recvs_edit_form').validate({
+	$('#recvs_edit_form').validate(
+	{
 		submitHandler : function(form)
 		{
 			var selected_supplier = autocompleter.val();
@@ -131,6 +153,9 @@ $(document).ready(function()
 			date: {
 				required:true,
 				date:true
+			},
+			invoice_number: {
+				invoice_number: true
 			}
 		},
 		messages: 
@@ -141,9 +166,11 @@ $(document).ready(function()
 			}
 		}
 	});
-	$('#recvs_delete_form').submit(function() {
+	$('#recvs_delete_form').submit(function() 
+	{
 		var id = $("input[name='receiving_id']").val();
-		$(this).ajaxSubmit({
+		$(this).ajaxSubmit(
+		{
 			success:function(response)
 			{
 				tb_remove();
diff --git a/application/views/sales/form.php b/application/views/sales/form.php
index 358436eef..7d8f659a2 100755
--- a/application/views/sales/form.php
+++ b/application/views/sales/form.php
@@ -76,7 +76,8 @@ $(document).ready(function()
 		}
 	});
 	
-	var format_item = function(row) {
+	var format_item = function(row) 
+	{
     	var result = [row[0], "|", row[1]].join("");
     	// if more than one occurence
     	if (row[2] > 1 && row[3] && row[3].toString().trim()) {
@@ -85,7 +86,8 @@ $(document).ready(function()
     	}
 		return result;
 	};
-	var autocompleter = $("#customer_id").autocomplete('<?php echo site_url("sales/customer_search"); ?>', {
+	var autocompleter = $("#customer_id").autocomplete('<?php echo site_url("sales/customer_search"); ?>', 
+	{
     	minChars:0,
     	delay:15, 
     	max:100,
@@ -95,21 +97,25 @@ $(document).ready(function()
     });
 
 	// declare submitHandler as an object.. will be reused
-	var submit_form = function(selected_customer) { 
-		$(this).ajaxSubmit({
+	var submit_form = function(selected_customer) 
+	{ 
+		$(this).ajaxSubmit(
+		{
 			success:function(response)
 			{
 				tb_remove();
 				post_form_submit(response);
 			},
-			error: function(jqXHR, textStatus, errorThrown) {
+			error: function(jqXHR, textStatus, errorThrown) 
+			{
 				selected_customer && autocompleter.val(selected_customer);
 				post_form_submit({message: errorThrown});
 			},
 			dataType:'json'
 		});
 	};
-	$('#sales_edit_form').validate({
+	$('#sales_edit_form').validate(
+	{
 		submitHandler : function(form)
 		{
 			var selected_customer = autocompleter.val();
@@ -121,20 +127,23 @@ $(document).ready(function()
 		wrapper: "li",
 		rules: 
 		{
-			date: {
+			date: 
+			{
 				required:true,
 				date:true
 			}
 		},
 		messages: 
 		{
-			date: {
+			date: 
+			{
 				required: "<?= $this->lang->line('sales_date_required'); ?>",
 				date: "<?= $this->lang->line('sales_date_type'); ?>"
 			}
 		}
 	});
-	$('#sales_delete_form').submit(function() {
+	$('#sales_delete_form').submit(function() 
+	{
 		var id = $("input[name='sale_id']").val();
 		$(this).ajaxSubmit({
 			success:function(response)