Sorry to do this to you but we need to cover the basics first. Can you ping the target host from the machine you're running the client side app from? Are you certain that the server side application is running on the target host? Are the firewalls off on both machines (this isn't 100% necessary but it rules them out as a cause to this problem)? Is the server side app listening on the same socket?
It sounds like your Server side is not responding correctly. On the PC running the Server application open a command prompt and type netstat -a -b and look for the name of your executable to make sure that it is in the 'LISTENING' state and double check which port it is listening on.