If you are not getting video there are a few things that could be causing that. Just want to know first, are you getting any audio and no video. If that is the case, you would want to check on the cables and what source you on, first. The Slingbox Pro HD does have a few different way to hook it up. If you have a HDMI cable hooked up to the cable box, you might be running into a content protection from the cable box. Here are a few articles that will help with the no video.
- Slingbox.com - Fixing "No video signal" problems with Setup on Slingbox.com
- Slingbox.com - Using an HDMI video source with the Slingbox 500
The second article will talk about the Slingbox 500, but I added it if you are using a HDMI cable from the cable box to the TV.
Hope this information helps!