unable to Upload photo on facebook wall in iphone sdk

In my iPhone app, I am trying to upload photo on facebook wall using this code.

It works fine when I am using in simulator, but when I try to upload from device it shows nothing on facebook wall.

EDIT: I am getting following error in console when running on device :

sendToPhotosFinished method :

Send To Photos Finished
ResponseString : {"error":{"type":"OAuthException","开发者_Python百科;message":"(#1) An unknown error occurred"}}
ResponseJSON : {
             error =     {
             message = "(#1) An unknown error occurred";
             type = OAuthException;
             };
}
Photo id is: (null)

and in getFacebookPhoto method :

Got Facebook Photo: {"error":{"type":"OAuthException","message":"(#803) Some of the aliases you requested do not exist: (null)"}}

While running in simulator I got all the values.

What could be wrong?

---

Did you pass the correct API key?

I think the problem is that you are not passing your API Key and hence it gives null.

That is where your problem lies.

http://www.insidefacebook.com/2010/11/17/api-test-user-developers/