To get a charge to the battery you need a supply to the fridge, and a permanent supply.
The fridge supply operates a relay in the caravan, which in turn allows the permanent supply to the battery.
Thats been the set up for Bailey since 2004, perhaps earlier.
So assuming you have both those supplies (and returns) to the caravan, and all the fuses are good, (as you say).
Then two possibilities to check, the relay could be faulty, or you could have a blown fuse adjacent the battery.
If you can get on mains hook up, then the fuse can be checked by testing for 13.7 volts at the battery.