Ignition. I have a reddy heater 35. When I plug it in the fan comes on, fuel dispenses, but then

Question

I have a reddy heater 35. When I plug it in the fan comes on, fuel dispenses, but then it trips the reset button. Why? When I removed the cover and repeated, I didn't see a spark at the spark plug but then again I don't know if it's supposed to be visible.