2004 Buick Ranier Low beam headlights

I started my vehicle last night and the headlights did not come on. I have the sensors that automatically turn them on. I have high beams, runnuing lights, tail lights, signal lights and fog lights, but no low beam. There are seperate fuses for each lamp, driver's side low beam, driver's side high beam and the same for the passenger side. I tried turning on and off the manual switch with no results. Other than fuses or bulbs, what would you suggest may be the problem?