We have the Slingbox PRO-HD, we have all the cables hooked up correctly based on the diagrams and other help sources.
The comcast cable goes directly INto the cable box (an HD DVR Scientific American 8300 HD). From the cable box we have an HDMI cable feeding directly to our HDTV. We do not want the cable signal routed through the slingbox to the TV and chose to run a separate cable signal from the cable box to the slingbox through the RGB cables. After setting everything up, the only feed we get is audio, however, if we disconnect the HDMI cable from the cable box the slingbox video works. We've checked that the signal is 1080i, and made sure all the cables are properly set up. We should not have to disconnect the direct feed via HDMI from the cable box to the TV to have slingbox working properly. Any help to figure this out would be greatly appreciated.