At one RV park I frequent in the Colorado Rockies I've found that even though the RV park calls it 'cable', it is really just the local channels broadcast from their DirecTV connection in the clubhouse.
I tried scanning with the TV set on 'cable' and got nothing but sound with a grainy, unwatchable picture.
For whatever reason, I set the TV back to 'antenna' and scanned, and suddenly I got all of the channels perfectly!
That being said...both RV's that I've bought brand new (both in the last five years) the entire coax setup in both were wired up completely backwards!
I made both of them work while out camping, then asked both different dealers to fix it right...
And when I got each one back (two different dealerships), they wired them both back up the way they came from the factory...backwards again!