Oven burner would not light.

I thought that when the burner didn't light it was the control valve at fault. After shutting off the gas, I changed the valve by removing the wires, undoing the tubing, then unscrewing the unit from the back of the unit. This worked one time. It turns out that if there isn't enough voltage from the burner, the valve won't open. I found this out after I mistakenly thought that the new valve was faulty. Check the voltage from the burner before you do anything else.