Doesn't work for Gamestats.com Rated 1 out of 5 stars

I just now installed this and tried it on the website gamestats.com. For some reason I don't get the 'Add to search box' option. When I try it on Firefox's add-ons page it DOES work.
Am I doing something wrong?

This review is for a previous version of the add-on (2.0.1-signed).