The four likely possibilities:
- The antenna booster is on (as Az Ernie said)
- The selector switch in RV is not set to CABLE for that TV...
- The signal source on the TV menu is not set to CABLE
- The park(s) use a QAM system which some TVs are not compatible with and you were just lucky the first time...
The first 3 are cheap fixes... The fourth needs a converter box or new TV.
I've hit the first 3 of those 4 at various times...