fix contract on validation

entity/Contract_entity/onValidation.js

@@ -13,7 +13,7 @@ if (!DateUtils.validateBeginnBeforeEnd(startDate, endDate))
     errorMessage = DateUtils.getValidationFailString();
 
 // check Duedate
-var cDue = vars.get("local.value");
+var cDue = vars.get("$field.CONTRACTDUE");
 if (cDue && (startDate && !DateUtils.validateBeginnBeforeEnd(startDate, cDue) || endDate && !DateUtils.validateBeginnBeforeEnd(cDue, endDate)))
 {
     if (errorMessage != "")