fix issue when saving mapping for date field - field set to null if no mandate org

CRM/Streetrecruitmentimport/Form/SrMapping.php

@@ -132,7 +132,7 @@ class CRM_Streetrecruitmentimport_Form_SrMapping extends CRM_Core_Form {
       $mandateOrganizationValue = $this->_submitValues['sr_mandate_organization_value'];
     }
     else {
-      $fieldDateFormat = NULL;
+      $mandateOrganizationValue = NULL;
     }
     // if name is empty, delete mapping
     if (empty($fieldMappingName)) {