PokerTracker - Observing on Poker Stars?

I just purchased PokerTracker tonight, and it looks like it's got a lot to offer. I want to maximize my reads on people, so I was planning on observing via Poker Stars, and letting hand histories build. I have Poker Stars set up to store my hand histories on disk, but it looks like it doesn't work unless I'm actually playing. I tried to get around this by taking a seat and sitting out, but still no luck.

Anyone got any ideas on how I can track without playing on Poker Stars?