Duster Headlights not working even with power?

Hey guys I have a 71 Duster slant 6 and went to flip on my headlights tonight and they don't work at all they've been working ok since I had the car the past few months. I replaced the dimmer switch because I read that was a common cause for headlight failure but no luck. So I got a tester and started poking around and noticed there's power all the way to the headlight sockets and shows power on the back of the headlight itself but still the headlights don't work. Any thoughts or comments would be great. Thanks.
Justin