I'm having a problem with StatTracker as well...I can't buy it.
Every time I try to purchase it, I get to the screen where you confirm, and I get a message saying there is a temporary problem, except it's lasted for over a week now. It says to contact Yahoo! Customer Care (15) but doesn't give any contact info. I sent an email to some customer help thing I found after searching, but never got a response.
I hate to sound so grouchy about it, but it's getting a bit ridiculous.