My 2008 Atwood Stove Igniter will not light one of my burners. The other two light just fine, but one I have to use a flame to light it. After it is lit, I can shut if off and I can immediately light it using the igniter. Don't understand why? I can see the spark the second time (after it is lit) but not the initial try(s). Any idea what would cause this and what I can do to fix it?