Hm.. I'll remove it from my forum, redownload the zip file and upload that XML file and then re-import it. I'll get back to you.
Edited to Add: This was definitely a mistake on my part. I feel a little embarassed now. :disappointed:
The problem was that I originally had the style set to non-selectable and then added this product and edited the settings to choose which groups could access it, but I never made the style selectable globally. Maybe you could add something about that to the instructions? Just to say that you need to have the style globally available for this product to function correctly.