12v issue

I have a 2004 arctic fox 990 camper, the radio stopped working and figured out it wasn't getting power so i found a 12v source and it works. Now the florescent light by the back door doesn't work, its not getting power to the fixture, i'm not very smart with electrical stuff so any suggestions on where to look or what to do keep in mind i'm not the brightest with this kind of stuff. All other 12v things work fine.

Kevin