Parking lights snafu

Today I am trying to get my parking lights on Barracuda to work. It is a '69 'Cuda. The socket for the turn signal and parking light is working because it lights my test light up. The bulbs are good because I tried them in the taillight sockets and they function correctly. I check the contacts on the parking light socket and they are functioning as they should. Put a bulb in the socket and nothing. WTH is going on??? Ground or incorrect bulbs?