facebook graph api: delete notification

string sURL = "https://graph.facebook.com/" + _requestID + "?access_token=" +  app.AccessToken + "&method=delete";

    WebRequest request = WebRequest.Create(sURL);
    request.Method = "DELETE";

I use this code to delete a开发者_如何学JAVAn apprequest. The request is removed from the list, but the notification is still there. Is there any way to delete it? Did i miss something when i am deleting the apprequest maybe? Thanks

---

Make sure that final generated request is like below:

DELETE https://graph.facebook.com/ID?access_token=... HTTP/1.1

Also make sure that you're access_token have actually have access to user posts.