Ignition system problem? Help!

I prefer (and you can make one) the ones that look like a big gap spark plug, but I also have one of these, which is adjustable

[ame="http://www.amazon.com/Lisle-50850-Ignition-Spark-Tester/dp/B0002STS44"]Lisle 50850 Ignition Spark Tester : Amazon.com : Automotive[/ame]