Duster Headlights not working even with power?

Just because you have voltage doesn't mean they'll work. The wires have to pass electrons, lots if them. You can measure 12 volts at the end of a wire the diameter of a human hair, but you couldn't suck enough electrons thru it to power up anything but maybe an electronic part.
It's like a brand new 9volt drycell; it has over 9 volts right, but it can't run hardly anything on your car; like maybe a dashbulb.
So yeah; you need power and ground, but you also need electron flow.