Do what is simple first. Take a bulb from another fixture in the camper and try it. That will eliminate the bulb. Check for corrosion on the contacts. Pull the panel where the switch is. Is there voltage getting to the switch and leaving it when you turn it on? If that is true then you likely have a bad ground for the light. Remove the light and trace the ground wire and clean where it connects to the frame.
Chuck - Sparta, TN
2012 Jay Flight 22FB, 2 x Honda EU2000i
2013 GMC Yukon XL Denali AWD
EDUCATION is what you get when you read the fine print.....
EXPERIENCE is what you get when you don't.