Side marker light dilemma.

'83 M923 left rear side marker light isn't working. Old light looked corroded so I replaced it with a new light. Still nothing. Checked for power and I've got power to the socket but the bulb won't light. Received a "bag of bulbs" with the truck when I bought it and tried numerous bulbs of the same number but still won't light up. Has anybody run into a bad light before? I'm stumped.

Check the grounds .

remember. Do that tomorrow. Thanks.