Has the emitter moved from where it was originally? It should be stuck on directly over the IR receiver inside the cable box. Get a flashlight and look for it. It looks like a round orb. Get really close to the bezel and shine the light in so that you can see it. If the emitter is a couple inches away it may not work.

Also.. you should have called the original company.. they could have resolved this with a 10 minute service call.