Aha. So you are trying to run a server... and it tells you that IC2 is missing?
Did you, by chance, download and install the IC2 1.337 Server software?
When you are playing "offline", you run the client - this is also what you will use to connect to a server. Your server, however, must be running the IC2 Server - even if it's on the same machine.
I'm sure someone here who does that sort of thing could tell you more.
Yeah, I know, that's the problem. I have both IC2-server1.337b at my server and IC2-Client1.337b at my client game.