Have you checked the electrical ground at the light?

I've experienced corrosion at that spot which caused the light to not work. After cleaning off the corrosion, thus restoring a good ground, the lights worked again.

Hope this helps, Dean

Have someone step on the pedal while you watch the light. If you can see when the light comes on, you can bypass the extra person. Press increasingly harder until the light comes on. If the brake light does not come on or if you have to press harder than it takes to stop the car normally, it's a bad switch. I was replacing pressure switches about every year and finally just bit the bullet and switched to a later, lever switch. I had no idea mine was bad until a member told me during a tour that my brake light wasn't working. It came on if I pressed the pedal hard enough to would have had to lock-up the brakes to get it to light.