Does the light operate properly when you flip the switch? if it doesnt then its wired wrong. If it does work properly then it could still be wired wrong. It is possible that even wired wrong that the indicator light on the switch can pull a ground through the power wire going to the device (i'm a mechanic and i've seen guys at my job do it).
I would check the wiring... sometime on the switch by the prongs there are really small labels molded into the plastic and if you look really close under good light you can read what they say.