Hi thanks for letting me join your group. A retired automotive engineer of 22 years, Ford and Toyota

IIRC bulb comes out from the back.
If you discover bulb is not burned out, it could be a grounding issue. Their is a little nub on the housing that supposed to dig through the paint into the sheetmetal.
If all this seems kosher, it`s most likely the switch on the trans. If 4 spd? the aftermarket is garbage from new.
I don`t know the quality of the auto switches.
Worse comes to worse their`s always a toggle switch route.