Problem Geting friends Facebook Sdk

Hi, i'm trying to load my friend list but the json that returns me is empty. I mean. i'm calling:

FB.API("me?fields=id,name,friends",Facebook.HttpMethod.GET,UserCallBack);

and the debug is:

Text: {"id":"10203896398915819","name":"Martin Gonzalez"}

Friends are missing so i cannot read them.

I have logged this way:

FB.Login("read_friendlists,email,publish_actions",FBCallback);

Any idea? Thanks!