This does not make any sense. You have fire, you have fuel. I would suspect lack of draft, No Oxygen. Is your flue blocked off with a birds nest, or some other obstruction? Do you have an exhaust fan running in the house pulling air back down the flue?
Since this is a stand alone pilot, get a flashlight. Crack a nearby window. Kill house power, and turn up the stat with the pilot on. See if she lights off.
Since this is a stand alone pilot, get a flashlight. Crack a nearby window. Kill house power, and turn up the stat with the pilot on. See if she lights off.