can you post the complete error message?

Are you using a alias for the connection?

Try connecting using IP address suffixed by the port no ( XX.XX.XXX.XX,portno) just on a test basis.

you can also take a look at the discussion from the following URL:

http://social.msdn.microsoft.com/Forums/en-US/csharpgeneral/thread/3ad597a2-2478-4844-92f8-444fe5063802/