The click is a good indicator that the store/use switch is good. Is it possible that you have a loose wire at the back of the Use/store switch? Or from the Use/store switch to the 12v panel? I would pull the Use/store switch and see if you have power in and out of the switch and then at the 12v fuse panel. The power should run from the battery to the circuit breaker to the use/store switch to the panel. You seem to have a break in that line somewhere.
__________________
|