ATI digital cable tuner and windows 7

I have an ATI Digital cable tuner with CableCard installed and activated for my FIOS Verizon service. When I try and set up the TV signal in WMC (I have a new Dell Zino running Windows 7) I get a message saying that no signal is detected. The tuner diagnostics show that the digital cable tuner and CableCard are receiving a signal, but for some reason WMC can't "see" it. I have updated the firmware for the tuner with no result. Anyone else having this problem? Any suggestions for a fix?
My Zino: 6850e at 1.8GHz and 4GB RAM
Thanks.

Yes it passes the digital cable advisor test.

The tuners do not have their own software. I have updated the firmware in the tuners to version 1.19 which is what is apparently required to function with Windows 7. Windows recognizes the USB plugged in tuner device and downloads and installs drivers on its own.