/statuses/mentions_timeline never returns anything



I’m using ZF1 and tmhOAuth and I need to display a clients mentions on their website.
I can get their tweets, but whenever I try to get their mentions (/statuses/mentions_timeline) nothing is returned, the response is always empty.

Below is what I’m using to get the mentions;

->request( 'GET', $this->_provider->url( '1.1/statuses/mentions_timeline', 'json' )   );

Any suggestions would be great.