UdpClient.Send的问题


public partial class UDPSocket : Component
    {
        private IPEndPoint ServerEndPoint = null;   //定义网络端点
        private UdpClient UDP_Server = new UdpClient(); //创建网络服务，即UDP的Socket
        private Thread thdUdp;  //创建线程
        public delegate void DataArriveEventHandler(byte[] Data, IPAddress IP, int port);   //定义数据到达托管事件
        public event DataArriveEventHandler DataArrival;    //通过托管，在空间中定义一个事件
        private string localHost = "127.0.0.1"; //定义本机地址
        [Browsable(true), Category("Local"), Description("本地ip地址")]     //在窗口设置本地ip地址
        public string LocalHost
        {
            get { return localHost; }
            set { localHost = value; }
        }        private int localPort = 11000;
        [Browsable(true), Category("Local"), Description("本地端口号")]  //在属性窗口显示本地端口号
        public int LocalPort
        {
            get { return localPort; }
            set { localPort = value; }
        }        private bool active = false;
        [Browsable(true), Category("Local"), Description("激活监听")]   //在属性窗口显示激活监听属性
        public bool Active
        {
            get { return active; }
            set
            {
                active = value;
                if (active)
                {
                    OpenSocket();   //打开监听
                }
                else
                {
                    CloseSocket();  //关闭监听
                }
            }
        }        public UDPSocket()  //构造函数
        {
            InitializeComponent();
        }        public UDPSocket(IContainer container)  //构造函数
        {
            container.Add(this);
            InitializeComponent();
        }        protected void Listener()   //监听
        {
            ServerEndPoint = new IPEndPoint(IPAddress.Any, localPort); //创建服务器地址
            if (UDP_Server != null)
                UDP_Server.Close();
            UDP_Server = new UdpClient(localPort);//创建新的端口号
            UDP_Server.Client.ReceiveBufferSize = 1000000000;//接收缓冲区大小
            UDP_Server.Client.SendBufferSize = 1000000000;//发送缓冲区大小            try
            {
                thdUdp = new Thread(new ThreadStart(GetUDPData));
                thdUdp.Start();//执行当前线程
            }
            catch (Exception e)
            {
                MessageBox.Show(e.Message);//显示线程错误信息
                //throw e;
            }
        }        private void GetUDPData()//获取当前接收的消息
        {
            while (active)
            {
                try
                {
                    byte[] Data = UDP_Server.Receive(ref ServerEndPoint);                    if (DataArrival != null)
                    {
                        DataArrival(Data, ServerEndPoint.Address, ServerEndPoint.Port);
                    }
                    Thread.Sleep(0);
                }
                catch
                {
                    //throw e;
                }
            }
        }        private void CallBackMethod(IAsyncResult ar)
        {
            //从异步状态ar.AsyncState中，获取委托对象
            DataArriveEventHandler dn = (DataArriveEventHandler)ar.AsyncState;
            dn.EndInvoke(ar);
        }        public void Send(IPAddress Host, int port, byte[] Data)
        {
            try
            {
                IPEndPoint server = new IPEndPoint(Host, port);
                int n = Data.Length;
                if (UDP_Server != null)
                {
                    UDP_Server.Send(Data, n, server);
                }
            }
            catch (Exception e)
            {
                MessageBox.Show(e.ToString());
                //throw e;
            }
        }        private void CloseSocket()
        {
            if (UDP_Server != null)
                UDP_Server.Close();
            if (thdUdp != null)
            {
                Thread.Sleep(30);
                thdUdp.Abort();
            }
        }
        
        private void OpenSocket()//打开
        {
            Listener();
        }
    }这是我写的组件，让我郁闷的是，在窗体调用是，每次使用Send方法发送数据的时候都会弹出一个小对话框，显示“未将对象引用设置到对象的实例”，不知哪里出了错误，望各位大哥指点。