Using "AsynchronousCient" socket, get exception "the target machin

[Sherry]

We are using the sample code "AsynchronousClient" from
http://msdn.microsoft.com/library/de...ketexample.asp.
It works for the wired (ethernet) connection. While the laptop is in wireless
environment, the laptop get exception:
"System.Net.Sockets.SocketException: No connection could be made because
the target machine actively refused it
at System.Net.Sockets.Socket.EndConnect(IAsyncResult asyncResult)
at Sender.AsynchronousClient.ConnectCallback(IAsyncRe sult ar)"

When the laptop is in wireless environment, it can ping the target machine,
and it's using port 2000.

Does anyone has experience on AsynchronousClient? We sincerely thanks for
the help.