Before I got a chance to tweak the electrode, a coworker suggested I put a pot on top of the stove before lighting it. I did, and the igniter works every time.
I've noticed that some people say that the piezo igniter performs excellently, while others say that it doesn't work well at all. My igniter sparks consistently, but the flame has never caught. I've tried with the gas a little and a lot open, but have gotten nowhere.
Could I be doing something wrong? Could I have just gotten a bad egg?