Several possible issues.
First. assuming you have the standared WINEGARD wall plate with an antenna connector on the front along awith a 12 volt outlet, Switch and light and 3 more cables on teh rear the center one is PARK CABLE IN.. This is the normal. if you have a different arrangement (Example A Matrix switch or Box of Many Buttons) well the cable port is clearly marked.
NOW.. On MY RV.. I have a problem with that cable.. I did some damage, fixed that but there is another break somewhere.. I use cable so little I've not yet gotten around to fixing it.. Will some day but alas. Not this week.
Many owners re-wire the switch (The wall plate) for Sat TV use re-routing cables.
Finally.. Some cable companies (I THINK Cox is one but dont' quote me) have gone from unencoded to all encrypted TV.. THeir reason.. PROFIT. back in the days of unencrypted TV you could put in a splitter and add more televisions but with ENCRYPTED you need a SET TOP BOX for each and every TV and thus they can rent you more boxes for a small additioanal fee.
Me I use Over the Air TG and skip the fee entierly.