php - Cannot identify db errors in codeigniter transactions -

so have code db transactions:

$to_return = true;         $this->db->trans_begin();          $this->insert_arrest_details($data);         $this->update_barangay($data['barangay_id']);         $this->insert_arresting_officers($data);         $folders = $this->insert_violators($data);           $this->insert_arrest_booking_form($data);            $this->insert_case_report($data);         $this->insert_seizing_officers($data['case_id'],json_decode($data['seizing_officers']));         $this->insert_items(json_decode($data['items']));         $this->insert_nitems(json_decode($data['nitems']));          $this->insert_violator_items(json_decode($data['items']));           $this->insert_violator_nitems(json_decode($data['nitems']));           if($this->db->trans_status() === false){             $array['error_message'] = $this->db->_error_message();             $array['error_number'] = $this->db->_error_number();              $this->db->trans_rollback();              $to_return = $array;         }else{               $img_success = $this->move_violators_images($folders);             $img_success = $this->move_items_images($data['case_id']);               $img_success = 1;             if($img_success == 1){                 $this->db->trans_commit();             }else{                 $this->db->trans_rollback();                 $to_return = false;             }          }                return $to_return; 

my problem is, if error (for example) occurs in $this->insert_arrest_details(); code doesn't error. returns this:

"error_message":"","error_number":0

but when tried run 1 method , method failed, code able error. why so?

your responses appreciated.