If you're trying to connect to a remote pool's getwork, you'll need their server address in the Pool addresses field, their getwork port in the Pool ports field, and an accurate Gateway so outgoing internet traffic knows where to start routing.

My initial reply was to pluMmet, using the mining_proxy command line. If you're using the mining proxy on a local machine, it might help to change the default getwork port (-gp option) and make sure to match the setting with the Pool ports field in your blade. If for some reason a local bitcoind is running on your machine, or some other software is using port 8332, it could hose up communications. That's a simple thing to rule out.