When I Send notification in facebook API by Unity. I've encountered an error. please help me fix this.

{
   "error": {
      "message": "(#606) You do not have permission to fetch notifications for this user",
      "type": "OAuthException",
      "code": 606
   }
}

You might want to have a look at this thread: http://stackoverflow.com/questions/12266593/how-to-use-new-client-side-facebook-notifications-api

I took the access_token of app.What should I do to try notifications API. I can't send notification api.