Did your aftermarket fog lights plug into the plugs supplied in the factory harness for the factory fog lights? If so, do the pins in the aftermarket fog lights wiring harness match up to the plugs in the factory harness plugs?
I am guessing when you installed your aftermarket fog lights, you cut the plugs off the factory harness and crimp fitted your aftermarket lights into the harness. I am guessing you have a bad (or missing) connection, which is not allowing the circuit to complete. As you know, if the circuit is broken your lights won't work.