Intermittent lighting on Victory Slant Fin Hot Water Heat...

I'm trying to help my parents get their heat working. I have troubleshot the electrical and everything is working as it should however the pilot will sometimes not light. The electronic ignition is zapping, and there is 24vac on the PV. I took a long wooden match and the pilot lit just fine. and the MV opened like a champ. Got heat. It would work properly 4 or 5 times in a row, then suddenly no lightum upum. Could the propane valve for pilot not be opening all the way? One other thing. How the heck does this thing know the pilot lit?