Piezo "knock" Help!!

I have an Arduino Duemilanove and recently attempted the "Knock" sensor tutorial, but I can't seem to get it to work. I used the same code from the examples tab and hooked everything up according to the picture on the tutorial page. I picked up the piezo at RadioShack, its voltage range is 30v max, and its curent consumption is 9mA max at 10vp-p, 2.5kHz square wave. I'm a beginner to the arduino, and most hadrware in general.

All help is appreciated, camelCase.

Nevermind. Got it working, I was just using the wrong resistor.