无法在android和c#中使用GCM推送通知

我已经在GCM中注册了我的设备，但我的推送GCM不起作用。我的代码有什么问题?

asp.net一边

protected void Button1_Click(object sender, EventArgs e)
{
    send("APA91bHwwSLPkdIfqxW8gsosp1J1zgUUsHsgY1LFxetxig4Abo3MfYg7mdbvU3gqLMN5VhW08HvHKhxsHzRAqbRs7WtE6jAQux77XZpx9_1p20O9LMrzpa9mw_RmXoyfq5bkxsLEHO7n6ZGWHzmfzZxaimp46GwR8g");
}
void send(string regId)
{
    try
    {

    var applicationID = "tokyo-***se-***12";

    var SENDER_ID = "8500****7538";
    var value = "push message";
    WebRequest tRequest;
    tRequest = WebRequest.Create("https://android.googleapis.com/gcm/send");
    tRequest.Method = "post";
    tRequest.ContentType = " application/x-www-form-urlencoded;charset=UTF-8";
    tRequest.Headers.Add(string.Format("Authorization: key={0}", applicationID));
    tRequest.Headers.Add(string.Format("Sender: id={0}", SENDER_ID));
    // string postData = "{ 'registration_id': [ '" + regId + "' ], 'data': {'message': '" + txtMsg.Text + "'}}";
    string postData = "collapse_key=score_update&time_to_live=108&delay_while_idle=1&data.message=" + value + "&data.time=" + System.DateTime.Now.ToString() + "&registration_id=" + regId + "";
    Console.WriteLine(postData);
    Byte[] byteArray = Encoding.UTF8.GetBytes(postData);
    tRequest.ContentLength = byteArray.Length;
    Stream dataStream = tRequest.GetRequestStream();
    dataStream.Write(byteArray, 0, byteArray.Length);
    dataStream.Close();
    WebResponse tResponse = tRequest.GetResponse();
    dataStream = tResponse.GetResponseStream();
    StreamReader tReader = new StreamReader(dataStream);
    String sResponseFromServer = tReader.ReadToEnd();
    lblStat.Text = sResponseFromServer;
    tReader.Close();
    dataStream.Close();
    tResponse.Close();
    }
    catch (Exception w)
    {
        Response.Write(w.Data);
    }
}

web . config

 <appSettings >
    <add key="GOOGLE_API_KEY" value="AIzaSyCuXwVivtKDKBqS2zxGCrD7Cc2Qwpjxgcw"/>
  </appSettings>

tRequest.Headers.Add(string.Format("Authorization: key={0}", applicationID));