Lang gas pizza oven.. Main burners won't lite!
Hello. It sounds like, from what you said, you have a new thermocouple. The device it is attached to, the pilot safety, could have a problem internally that allows gas to the pilot, but does not open the main part of the valve, or electrically has failed on the main coil. If you have a thermostat with wires on it, you can jumper the wires, to bypass it, temporarily please, if it comes on, you need a thermostat, if not, it is the valve most likely.
Hope that helps, and thank you.