[Ihatemowing]

Next I would check the spark to make sure it is bright blue and strong. It's not totally out of the realm of the possible to have a bad plug right out of the box.

I second the weak or no spark idea. if there is no spark throught the plug don't forget to try it w/o the plug. stick a screwdriver into the plug wire and set it near the block pull it over slowly if there is still no spark it could be the coil.