Planetary Napalm not working Demo 1.08

I have ordered the full game but it has not arrived so I am playing the demo. I could not use Planetary Napalm on a planet, I had placed it in a missile frigate and gave specific orders to target the planet using the napalm, instead it fired the missile, despite having over 1000 supplies in engines and 800 ordinance in pods & missile (it only requires 5 supplies to fire the Napalm) is this a recognised bug, what is the work around ?