No video signal on HDTV but computer sees the new display

I have the UGA-2K-A adapter on a 32-bit Windows XP machine (latest service pack). I have the adapter connected to an HDTV. Everything looks like it’s fine, the computer sees the monitor and acts as all is ok. Even using Logmein I can see and use the new monitor. However, no video displays on the TV no matter what I try. I saw either here or on displaylink that it may be a problem with the latest firmware, so I uninstalled the latest and rolled back to the previous stable version they recommended. Still no luck. Any ideas?