No video and a new cable box, huh? It sounds like you require assistance with reconfiguring your Slingbox to your new cable box. The first step you need to take would be to perform a factory reset on the Slingbox. Once you have completed the reset (and have both solid power and network lights), you would then rerun through initial setup just like you did when you first setup the Slingbox.
Here are some links to get you setup:
Please get back in touch with us if you still are not getting video after attempting setup.
Sling Media Forum Moderation Team