 <p><code>Call to a member function GetUserDocumentFolders() on a non-object</code></p> <p>That error means that $this->client is not an object, more than likely its null and has not been set yet.</p> <p>You have to set <code>$this-&gt;client</code> to an instance of whatever class has the <code>GetUserDocumentFolders</code> function</p>