function isIncompleteCause() { //define your own isIncompleteCause rules with MyShopOrder.php $this->isIncompleteReasons = null; try { $this->isIncompleteReasons = parent::isIncompleteCause(); return $this->isIncompleteReasons; } catch (Exception $e) { ShopOrder::displayExtensionNoticeFor("ShopOrder::isIncompleteCause"); return null; } }