nov/fb_graph — pull request #276 by kimlima (2012-11-12 14:38:41+00:00)
Title: Added fields option to FbGraph::User

Some fields of the User object must be specifically requested via the fields parameter including the fields third_party_id, installed, cover, currency, picture, security_settings and video_upload_limits. (See: http://developers.facebook.com/docs/reference/api/user/).

I solved my problem adding a fields option to User and Node.