관리자모드 들어갈려고 하면.. 오류메세지가 뜨는데요..

Fatal error: Call to a member function getAction() on a non-object in /home1/coninside/public_html/zbxe/classes/db/DB.class.php on line 420

420번째 줄 봐도 뭘 어떻게 고쳐야 될찌 모르겠습니다..

 // execute appropriate query
        switch($output->getAction()) { <- 420번
                case 'insert' :
                        $this->resetCountCache($output->tables);
                        $output = $this->_executeInsertAct($output);
                    break;
                case 'update' :
                        $this->resetCountCache($output->tables);
                        $output = $this->_executeUpdateAct($output);
                    break;
                case 'delete' :
                        $this->resetCountCache($output->tables);
                        $output = $this->_executeDeleteAct($output);
                    break;
                case 'select' :
                        $arg_columns = is_array($arg_columns)?$arg_columns:array();
                        $output->setColumnList($arg_columns);
                        $connection = $this->_getConnection('slave');
                        $output = $this->_executeSelectAct($output, $connection);
                    break;
            }

고수님들 알려주세요~