I don't think so it can be the reason. Because I am able to take the post information from my Facebook account. If I am able to take posts from my account logically there should not be a problem to take comments. There must be some technical issues which I am not able to solve. Logically there should not be any issue. My guess is I am using FQL to retrieve my post and comment. But Facebook is switching to Graph API. On the other hand Mathematica is improving towards natural language. That may work. May be I need to change my old code to new. This is my speculation. Not sure. Correct me if I am wrong.