想和服务器进行通信，现在的问题我是我可以向服务器发送请求，但是收不到服务器的返回数据，下面是代码，还请好心人给分析下怎么修改。

 public bool CheckVersion(string comNum) //查看终端版本信息
        {
            try
            {
                IPAddress address = null;
                if (IPAddress.TryParse(userIpAddr.Trim(), out address))
                {
                    if (sockCenter != null)
                    {
                        sockCenter.Close();
                    }
                    EndPoint remoteEP = new IPEndPoint(address, userPort);
                    sockCenter = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
                    sockCenter.Connect(remoteEP);
                }
                if((this.sockCenter != null) && this.sockCenter.Connected)
                {
                    sockCenter.BeginSend(temp, 0, temp.Length, SocketFlags.None, null, null);
                    return true;
                }
            }
            catch (Exception)
            {
                return false;
            }
        }
       

        public void GetVersion()
        {
            if (threadCenter != null)
            {
                threadCenter.Abort();
            }
            threadCenter = new Thread(new ThreadStart(ReadCenterData));
            threadCenter.IsBackground = true;
            threadCenter.Start();
        }
       

        public void ReadCenterData()
        {
            int num = 0;
            byte[] buffer = new byte[0xc800]; //51200
            //sockCenter.Accept();
            try
            {
                while (true)
                {
                    num = sockCenter.Receive(buffer, 0, sockCenter.Available, SocketFlags.None); //接收指定的字节数,参数3
                    if (num == 0)
                    {
                        num = sockCenter.Receive(buffer, 0, sockCenter.Available, SocketFlags.None);
                        if (num == 0)
                        {
                            if (sockCenter != null)
                            {
                                sockCenter.Close();
                            }
                            return;
                        }
                    }
                }
            }
            catch
            {
                if (sockCenter != null)
                {
                    sockCenter.Close();
                }
            }
        }

发送正常，就是receive的时候，sockCenter.Available一直为空，要怎么修改呢？