android Facebook oAuth exception?

I am getting this response from facebook while trying to postwall. {"error":{"messa开发者_开发知识库ge":"An active access token must be used to query information about the current user.","type":"OAuthException"}}

can anybody help me what can be a problem?

{"error":{"message":"An active access token must be used to query information about the current user.","type":"OAuthException"}}

This error comes when your Access token gets Invalid. So you need to Authenticate the user again in order to get a Valid Access Token.

You have not added the permission correctly.