异步套接字不'；不起作用

我正在用套接字构建一个自定义HTTP请求类。我的代码是基于MSDN异步套接字Guid的，但不幸的是它不起作用。请求运行良好，但我没有收到完整的响应。也许有人能帮我解决这个问题吗？这是我的代码：

private void BeginConnect()
{
    //Connect To Server
    Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
    socket.BeginConnect(this.ResolveUrl(_requestUri), new AsyncCallback(this.ConnectCallback), socket);
}
private void ConnectCallback(IAsyncResult ar)
{
    //Get Socket
    Socket socket = (Socket)ar.AsyncState;
    //Complete Connection
    socket.EndConnect(ar);
    //Send HTTP Request
    byte[] requestBytes = this.CreateRequest();
    socket.BeginSend(requestBytes, 0, requestBytes.Length, SocketFlags.None, new AsyncCallback(this.SendCallback), socket);
}
private void SendCallback(IAsyncResult ar)
{
    //Get Socket
    Socket socket = (Socket)ar.AsyncState;
    //Complete Sending
    socket.EndSend(ar);
    // Create the state object.
    StateObject state = new StateObject();
    state.WorkSocket = socket;
    //Recieve Response
    socket.BeginReceive(state.Buffer, 0, StateObject.BufferSize, SocketFlags.None, new AsyncCallback(this.ReceiveCallback), state);
}
private void ReceiveCallback(IAsyncResult ar)
{
    //Get StateObject
    StateObject state = (StateObject)ar.AsyncState;
    Socket socket = state.WorkSocket;
    //Complete Receiving
    int bytesRead = socket.EndReceive(ar);
    if (bytesRead > 0)
    {
        //Save Already Received Data
        state.ResponseBuilder.Append(Encoding.ASCII.GetString(state.Buffer, 0, bytesRead));
        //Get Rest Of The Data.
        socket.BeginReceive(state.Buffer, 0, StateObject.BufferSize, SocketFlags.None, new AsyncCallback(this.ReceiveCallback), state);
    }
    else
    {
        if (state.ResponseBuilder.Length > 1)
        {
            //Shutdown Socket
            socket.BeginDisconnect(false, new AsyncCallback(this.DisconnectCallback), state);
            //Invoke Callback
            SocketResponse resp = new SocketResponse(state.ResponseBuilder.ToString(), HttpStatusCode.Accepted); //TODO
            _callback.Invoke(resp);
        }
    }
}
private void DisconnectCallback(IAsyncResult ar)
{
    //Get Socket
    StateObject state = (StateObject)ar.AsyncState;
    Socket socket = state.WorkSocket;
    //Shutdown Socket
    socket.Shutdown(SocketShutdown.Both);
    socket.Close();
}