帮忙看一个不稳定的异步UDP接收数据程

[ybdesire]

//begin rcv
private void button1_Click(object sender, EventArgs e)
{
IPEndPoint p = new IPEndPoint(IPAddress.Any, Convert.ToInt32(textBox3.Text));
UdpClient u = new UdpClient(p);
u.BeginReceive(new AsyncCallback(ReceiveCallback), u);
}
public void ReceiveCallback(IAsyncResult result)
{
UdpClient u = (UdpClient)result.AsyncState;
IPEndPoint p = new IPEndPoint(IPAddress.Any, Convert.ToInt32(textBox3.Text));
byte[] recvData = u.EndReceive(result, ref p);
string rData = Encoding.Default.GetString(recvData);
textBox1.Invoke(settextboxrecvcallback, rData);
u.BeginReceive(new AsyncCallback(ReceiveCallback), u);
}
内网通信，为什么在有的电脑上运行能接收，在有的电脑上运行就接收不到任何数据呢？
用“网络调试”助手测试过，所有电脑都能接收....
请大神帮忙看看我这程序哪里有问题？？？？？？？？