I am hooking up another room got an HD box from Comcast. Hooked it all up but then nothing. I called Comcast she tried everything she could but didnt get a signal back from the box offered to send a tech but I think it would be best to make sure I didnt make any mistakes. hooked up a 3 way to add another TV but it just isnt working anything to check any ideas??

Have the tech come and make sure that the wiring is set up correctly and that the new receiver is working.