a plug can have spark, but still be bad. the reason;
spark plugs work in a similar matter to a glow plug. the ceramic core heats up to a certain temperature. the spark ignites the fuel/air mix and the red hot ceramic core completes the burn. that is why plugs have different heat ranges. they are calibrated to work with specific engine displacements.
but you say you have no spark at all, so its going to be something in that list i posted.