If the Slingbox is connected properly, the issue could be due to either a faulty video cable, output on your set-top box, or input on the Slingbox. To test this, you can run the cable directly from the set-top box to your television. If the problem persists, it's either the set-top box (in which case you could resolve the issue with your content provider) or the video cables (in which case you simply replace them).
Hope this helps!
The Slingbox Answers Forum Moderation Team