perdidohate:
So i' don't know why but i'm quite sure now that what we have in our hand is different from the piezo's shown on the Starter Kit page.
Sometimes people will try to use a piezo buzzer thinking it's a piezo speaker. The buzzer has some active electronics to play a tone when the buzzer is connected to power. The speaker is just a piezo element and will do nothing when connected to power.
You want a piezo speaker or piezo element, not a piezo buzzer.
You can often find drum-machine toys at thrift stores and yard sales. Each pad has a piezo element.