C# BeginReceiveFrom（）是否为空？

我一直在尝试在windows.net套接字中设置UDP客户端/服务器。 在下面的客户机脚本中，当客户机“连接”时，我能够向服务器发送消息，但当我尝试调用BeginToReceive（）函数时，我得到一个空引用

我不明白为什么我可以发送消息（当然是使用服务器端点），但由于空错误而无法接收。我是新来的插座，我想知道为什么这是不工作

服务器运行在windows c#应用程序中，客户端运行在Unity3D中的c#脚本中

private EndPoint epServer;
private Socket clientSocket;
private byte[] myBuffer = new byte[1024];

private void ConnectToServer ( ) {  
    clientSocket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
    IPEndPoint server = new IPEndPoint(IPAddress.Parse("127.0.0.1"), 61456);//Connect to the Local server 
    epServer = (EndPoint)server; //Access the server

    WritePacketAndSend("Hello Server");//This creates the packet and uses the BeginToSend() function to send the string to the server

    try{
         clientSocket.BeginReceiveFrom(myBuffer, 0, myBuffer.Length, SocketFlags.None, ref epServer, new AsyncCallback(ReceiveData), epServer);//<<< Null reference here not sure why...
    } catch(Exception ex) {
         print(ex.Message); //Keep getting: Object reference not set to an instance of an object
    }
}

private void ReceiveData(IAsyncResult ar){

   print("Entered ReceiveData");//The code never enters here

  try{                              
       IPEndPoint server = new IPEndPoint(IPAddress.Parse("127.0.0.1", 61456);
       epServer = (EndPoint)server;
       clientSocket.EndReceiveFrom(ar, ref epServer);

       clientSocket.EndReceive(ar);     

       print(Encoding.UTF8.GetBytes(myBuffer));

       clientSocket.BeginReceiveFrom(myBuffer, 0, myBuffer.Length, SocketFlags.None, ref epServer, new AsyncCallback(ReceiveData), epServer, 

      } catch (Exception ex){
          print("Receive Data: " + ex.Message); 
      }
   }

私有端点epServer；
私有套接字clientSocket；
私有字节[]myBuffer=新字节[1024]；
私有的void ConnectToServer（）{
clientSocket=新套接字（AddressFamily.InterNetwork，SocketType.Dgram，ProtocolType.Udp）；
IPEndPoint server=new IPEndPoint（IPAddress.Parse（“127.0.0.1”），61456）；//连接到本地服务器
epServer=（端点）server；//访问服务器
WritePacketAndSend（“Hello Server”）；//这将创建数据包并使用BeginToSend（）函数将字符串发送到服务器
试一试{
clientSocket.BeginReceiveFrom（myBuffer，0，myBuffer.Length，SocketFlags.None，ref epServer，new AsyncCallback（ReceiveData），epServer）；//ReceiveData的代码在哪里？刚刚添加了新代码。ReceiveData的代码在哪里？刚刚添加了新代码。