osterichs on "Zend Gdata Fatal Error on wordpress plugin directory"

hey, i have a question about gdata youtube.
i've devolp my plugin for wordpress and when add post it's getting error like this

Fatal error: Call to a member function resetParameters() on a non-object in /home/altereg1/demo_html/wp-content/plugins/osTube/Zend/Gdata/App.php
on line 644

and code on line 644 is

$this->_httpClient->resetParameters();

but when i try it on web root (outside wordpress) it's working good here the sample http://dev.alteregogi.com/Youtube/