Dome light???

I can not seem to figure out why the dome light.....the one over the back seat will not work. I have put a new bulb in, nothing. I hook up a voltmeter to the thing and nothing, i take off the switch and plate thing and there is no voltage comming directly from the wires. Is there a seperate fuse for this thing?? I thought that it would be fused in with the curtousey lights, since i believe it's suppose to turn on when you open the door. I am really frustrated........someone help.