MC - one cabelcard doesn't get new channels

I have a Win7 MC (ultimate x64) with 2 ATI TV Wonder USB cablecard tuners. I just upgraded from Comcast digital starter cable to digital preferred. This adds a bunch of channels. However, only one of my cablecards can get the new channels. I called Comcast several times and they claim they were able to contact both cablecards and download the access information; so they claim the problem is in my PC or MC. Has anyone else seen anythgin like this? Does anyone know of a way to check the list of channels scanned for each card? I've looked around the registry and didn't find it there. Thanks.

When you did the channel scan, did you just select the first tuner?