First off I hope that reset has been pressed very few times!! Pending on the problem the fire box can fill with oil resulting in a dangerous situation should it light off.O.K. make these checks. Is there oil in the tank? One time I was fooled by a bad tank gauge. Showed 14 but was actually empty! Are all the oil line vales open? When was the oil filter last changed? The oil line could be plugged[algae] the nozzle could be clogged,also the ignition transformer might be shot or possibly the oil primary [cad cell relay or stack switch ]may be acting up.also the the oil pump might be clogged or bad.Call a technician if it's more than you can handle. Good luck!