The cable connection in the outside bay was intended for use in the days when campgrounds provided cable service, which some still do. However, most do not, and with the proliferation of satellite dishes, it will continue to go away.
Chances are, if you have a DirecTV receiver, there has been a retrofit by the PO, and the cable from the bay is no longer available, since the user chose to go to satellite instead of cable.
This is purely conjecture on my part, but its what I ran into when putting in DirecTV and a new surround sound.
Stan