Fatal error: Call to a member function resetParameters() on a non-object

[alteregogi]

when i using gData for retrieving youtube video there have a problem and showing error

Fatal error: Call to a member function resetParameters() on a non-object in C:\wamp\www\wordpress\wp-content\plugins\osTube\Zend\Gdata\App.php on line 643

and the problem not appear if i try my function to root folder (ie. C:\wamp\www\youtube\ ) using same function for plugin and custom .php file for showing youtube video by playlistfeed.

this is app.php line 640 - 644

    // Make sure the HTTP client object is 'clean' before making a request
    // In addition to standard headers to reset via resetParameters(),
    // also reset the Slug and If-Match headers
    $this->_httpClient->resetParameters();
    $this->_httpClient->setHeaders(array('Slug', 'If-Match'));

btw i try to adding this zend gdata to my wordpress plugin.