GCM推送通知，c# asp.net在android设备上给出null作为通知

我正在c#中创建一个类，该类具有在android中使用GCM发送推送通知的方法。这种方法效果很好，也给了谷歌作为成功的回应。但在android模拟器中，通知是空的。下面是我使用的代码，

public void NotifyTest(string regId)
    {
        var applicationID = "AIza*************"; 
        var SENDER_ID = "xxxxxxxxxx"; 
        var httpWebRequest = (HttpWebRequest)WebRequest.Create("https://android.googleapis.com/gcm/send");
        httpWebRequest.ContentType = "application/json";
        httpWebRequest.Method = "POST";
        httpWebRequest.Headers.Add(string.Format("Authorization: key={0}", applicationID));
        httpWebRequest.Headers.Add(string.Format("Sender: key={0}", SENDER_ID));
        using (var streamWriter = new StreamWriter(httpWebRequest.GetRequestStream()))
        {
            string json = "{'"registration_ids'":['""+ regId +"'"]," +
                        "'"data'": { '"score'" : '"1234'"}}";
            Console.WriteLine(json);
            streamWriter.Write(json);
            streamWriter.Flush();
            streamWriter.Close();
            var httpResponse = (HttpWebResponse)httpWebRequest.GetResponse();
            using (var streamReader = new StreamReader(httpResponse.GetResponseStream()))
            {
                var result = streamReader.ReadToEnd();
                Console.WriteLine(result);
            }
        }
    }

代码正在工作，没有任何错误，并从谷歌返回响应。请让我知道你的建议。