Fios Cablecard Problem

I am having some issues with this ATI external cablecard tuner. Verizon was out the other day to install the cablecard. The tech tried three different cards and could get none to work. I set up the tuner before he arrived and was able to get all the unscrambled Fios channels. However the scrambled channels will not come through after three different cards, the first two were M-cards and the last one which is in there now is a S-card.

I already have another HTPC set up with an ATI internal cable card tuner and it works fine. He took readings at various points along the coax and found no problems. Of course he believes it's the tuners fault. Do you have any ideas of what could be wrong?

Connected how? The FIOS coax is connected to the tuner and it is unscrambling the channels. The PC is also connected via LAN to the the home network with internet access. I have Fios TV, Internet & phone service, nothing else, except an outside antenna which is connected directly to the TV's tuner.

Funny thing is, on the new HTPC, before the cablecard was installed, I could only get the unscrambled local HD channels on 3-1,6-1,10-1, and so on. After the card was installed I got the local HD on 503, 506, 510, etc. plus the SD locals on 003, 006, 010, etc. Makes me think it's the card or it's programming, not the tuner.