What is the problem on my rear right stop/turn light?

I have a 1990 F350 super duty truck, the rear stop/turn light doesn’t work. It has voltage, light bulb and connector are new and connection is good, is some thing else I need check?

Seems like this would be impossible if you have voltage at the socket and the bulb is good. Only thing lieft is contact between the bulb and socket. I’d go back and recheck the work though. Even new bulbs can be bad. I’d maybe try aligator clips from the socket to the bulb to see if it works or not.