Nieautoryzowany podczas dzwonienia do Google GCM

Próbuję użyć Google GCM do wysyłania powiadomień push. Ale zdobądź wyjątek WebException, który mówi, że zdalny serwer zwraca 401 nieautoryzowany. Nie mogę przestać się zastanawiać, dlaczego to nie działa.

Ktoś, kto wie, dlaczego to nie działa?

Oto mój kod:

            ServicePointManager.ServerCertificateValidationCallback += new RemoteCertificateValidationCallback(ValidateServerCertificate);

           HttpWebRequest Request = (HttpWebRequest)WebRequest.Create("https://android.googleapis.com/gcm/send");


            Request.Method = "POST";
            Request.KeepAlive = false;

            string postData = "{ 'registration_ids': [ '"+registrationId+"' ], 'data': {'message': '"+message+"'}}";

            byte[] byteArray = Encoding.UTF8.GetBytes(postData);

            Request.ContentType = "application/json";
            //Request.ContentLength = byteArray.Length;


            //Request.Headers.Add(HttpRequestHeader.Authorization, "GoogleLogin auth=" + AuthString);
            Request.Headers.Add(HttpRequestHeader.Authorization, "Authorization: key=AIzaSyCEygavdzrNM3pWNPtvaJXpvW66CKnjH_Y");
            //-- Delegate Modeling to Validate Server Certificate --//


            //-- Create Stream to Write Byte Array --// 
            Stream dataStream = Request.GetRequestStream();
            dataStream.Write(byteArray, 0, byteArray.Length);
            dataStream.Close();

            //-- Post a Message --//
            WebResponse Response = Request.GetResponse();
            HttpStatusCode ResponseCode = ((HttpWebResponse)Response).StatusCode;
            if (ResponseCode.Equals(HttpStatusCode.Unauthorized) || ResponseCode.Equals(HttpStatusCode.Forbidden))
            {
                var text = "Unauthorized - need new token";

            }
            else if (!ResponseCode.Equals(HttpStatusCode.OK))
            {
                var text =  "Response from web service isn't OK";
            }

            StreamReader Reader = new StreamReader(Response.GetResponseStream());
            string responseLine = Reader.ReadLine();
            Reader.Close();

questionAnswers(2)

yourAnswerToTheQuestion