the first thing to do is verify you have good lamps (bulbs). believe it or not, sometimes it is that simple.
do you have some means to test for voltage? If so, check for voltage from the shell of the socket to the contact at the bottom. (obviously make sure switch is on). Then, if nothing with that check, check from the contact at the bottom to a known good ground.
The Following User Says Thank You to nap For This Useful Post: