Need help with brake light on 1991 Mazda 323

I have one brake light not working, bulb is brand new, electrical looks fine, what could be the problem?

Asked by for the 1991 Mazda 323
2 answers 1 comment
used a test light check for juice at the socket of the bulb, make sure you have a good ground.
ground is good, and juice is going to all but one bulb?
Check and clean the soldered contacts and the body ground of your bulb socket. Make sure the contacts are touching with the bulb.