Odd DataWriter Issue

[silence]

I created a simple datawriter but I'm getting this issue that I'm not sure how to solve:

 Fatal error: Call to a member function result_metadata() on null in /home/fdsafdsafdsa/public_html/xenforo/library/Zend/Db/Statement/Mysqli.php on line 220

Tell me if you need more info, I'm just wondering what this is.

 

[truonglv]

Put more code here. It a little information so difficult to anyone want to help

 

[Daniel Hood]

Yeah, we need the stack trace. It looks like the query returned false instead of the statement object which is really weird.

 

[silence]

Yeah, we need the stack trace. It looks like the query returned false instead of the statement object which is really weird.

There is no stacktrace, just this:
Fatal error: Call to a member function result_metadata() on null in xenforo/library/Zend/Db/Statement/Mysqli.php on line 220

 

[silence]

Here is what I'm doing exactly:

Controller:

    public function actionSave()
    {
        $this->_assertPostOnly();

        $serverId = $this->_input->filterSingle('server_id', XenForo_Input::UINT);

        $input = $this->_input->filter(array(
            'server_host' => XenForo_Input::STRING,
            'server_port' => XenForo_Input::UINT,
            'query_port' => XenForo_Input::UINT,
            'server_password' => XenForo_Input::STRING,
            'rcon_password' => XenForo_Input::STRING,
            'server_type' => XenForo_Input::STRING,
            'active' => XenForo_Input::BOOLEAN,
            'category_id' => XenForo_Input::UINT,
            'display_order' => XenForo_Input::UINT
        ));

        $writer = XenForo_DataWriter::create('XenoGamers_GameServers_DataWriter_Servers');

        if ($serverId)
        {
            $writer->setExistingData($serverId);
        }

        $writer->bulkSet($input);
        $writer->save();

        return $this->responseRedirect(
            XenForo_ControllerResponse_Redirect::SUCCESS,
            XenForo_Link::buildAdminLink('gameservers/servers') . $this->getLastHash($serverId)
        );
    }

DataWriter:

    protected function _getFields()
    {
        return array(
            'xf_gs_server' => array(
                'server_id' => array('type' => self::TYPE_UINT, 'autoIncrement' => true),
                'server_name' => array('type' => self::TYPE_STRING, 'maxLength' => 200, 'default' => new XenForo_Phrase('unknown')),
                'server_host' => array('type' => self::TYPE_STRING, 'maxLength' => 200),
                'server_port' => array('type' => self::TYPE_UINT, 'default' => 0),
                'query_port' => array('type' => self::TYPE_UINT, 'default' => 0),
                'server_password' => array('type' => self::TYPE_STRING, 'maxLength' => 200),
                'rcon_password' => array('type' => self::TYPE_STRING, 'maxLength' => 200),
                'server_type' => array('type' => self::TYPE_STRING, 'maxLength' => 20),
                'category_id' => array('type' => self::TYPE_UINT,
                    'verification'   => array('$this', '_verifyServerCategory')
                ),
                'active' => array('type' => self::TYPE_BOOLEAN, 'default' => true),
                'display_order' => array('type' => self::TYPE_UINT, 'default' => 1)
            )
        );
    }