Pilot lights but when ignition pops back up the flame goes out

will either be the unitrol control box or the thermocouple, when you push down you are holding two magnets together and waiting for a small charge to be created from the probe in the flame , if this is not working you have no charge and the magnets won;t stick to allow the valve to open, change the thermo and see if that works first, its way cheaper than a new controler