They should not be a separate switch .... they should be linked into your main beam / flash.
Obviously the first thing to check is the bulbs .... otherwise it could be a number of things - if nothing obvious you might want to drop it in to an auto electrician to run a couple of tests on the circuit.
Additional driving lamps on your model also need coding on the ecu .... if this wasn't done when they were fitted you will have to get that done at the stealers