Yeah I was just reminded of this last spring....again!
When you are trying to hook up the cable to the sat box, and don't get a signal it is very important to make sure you turn off the antenna booster!
Typically it has a light by it to indicate that it is on. It may be near the rear TV. but it controls the antenna to both/all the TV's.
Judy & Ralph, w/Molly (the Westie) & Sadie (the Fourche Terrier)
2011 Ford F350 6.7 Lariat
2013 Infinity 3850RL