I tested the extension in FF2 and it works fine. So I don't know what the deal is.
I went ahead and put in a Bugzilla report for FF3 to see if it can get fixed. I'm sure they have a lot of work to do, so I don't expect it to get fixed anytime soon.
Sportsfox is a Firefox extension that allows you to keep your sports scores in a handy browser location. Sportsfox includes scores for NFL, NBA, WNBA, NHL, College Football, Men's College Basketball, and Women's College Basketball. Generally you should be able to download the latest version at Mozilla addons