Well, first, check to make sure it's not just turned off - some campers have a switch for it, or it might be unplugged, check the breakers, etc.
But even if it is off and does work fine, it's worth upgrading - the old univolts only put out a single voltage that will kill your battery unless you're careful to turn it off when it's done charging. The three stage models available today are much smarter and shouldn't do that.
1995 Airstream Classic 30' Excella 1000
2014 Ram 2500 Crew Cab with Cummins 6.7L Diesel
Sold but not forgotten: 1991 Airstream B190
Sold: 2006 F-250 6.0L Powerstroke Supercab