I have a Glow worm back boiler which will not fire up !?

The re-start button has the red light on, so when you press to manually start the boiler you can hear it sparking for a few seconds, a green light comes on and then the blue flame pops up, but then the sparking sounds quieter and then stops and the red light comes on. Could it be the spark generator !!
(Glow- worm inset fire with back boiler)