If pilot light is okay, most have a bulb that is heated by the pilot light. The bulb gets hot and generates an extremely small voltage that opens the main gas valve for the burner. If the bulb can be removed where it meets the main gas valve. remove it and clean the electrical contact on the bulb. It doesn't take much buildup to lose voltage. Be sure to sht off the gas first. Also clean bulb at pilot (soot). If still no work, Remove burner and look for a spider web inside the orifice at burner. The orifice (usually brass w/small opening) on the end of the tube that supplies gas from gas valve. Burner usually rests on the orifice. Spiders love gas.
Moonpie, October 2009