Most likely you are hooking up to the cable in jack on the trailer (motorhome?). That cable runs to the antenna amplifier plate and has a DC voltage blocker to prevent the amp from feeding voltage into the cable system (cable companies probably don't like it). Unfortunately your tailgater (and all satellite dishes) need that voltage to operate. You will either have to run a separate cable to the outside or that the cable off the amp.
2013 Coachman Mirada 29DSSE