diff --git a/src/org/openbravo/costing/PriceDifferenceUtil.java b/src/org/openbravo/costing/PriceDifferenceUtil.java
--- a/src/org/openbravo/costing/PriceDifferenceUtil.java
+++ b/src/org/openbravo/costing/PriceDifferenceUtil.java
@@ -48,7 +48,7 @@
         + " AND trx.client.id = :clientId)";
 
     if (!productIds.isEmpty()) {
-      strUpdate = strUpdate.concat(" AND product.id IN :productIds ");
+      strUpdate += " AND product.id IN :productIds ";
     }
 
     Set<String> products = new HashSet<String>();