Electrical Questions? Ask an Electrician Online.
Hi, I'm Mike G and I'll be glad to assist you. It seems that you have a short circuit in the fixture, the switch opening or the wiring between the two. The first thing to do is to remove the fixture and flip the switch to find out if it is the fixture causing the issue. A short will be obvious, there will be flash marks.
You need to find the short first. The cost for correction will be directly related. It may be as little as $.15 for a wirenut or the cost of a new fixtures. Follow my instructions and I'll be able to be more specific.