Product theme cannot find stylesheet

I've just installed the Product theme but all that is displayed are three lines saying "Please login and add widgets to this column" - no stylesheet, even when I manually select one from the theme options.

Any idea why it is not finding the stylesheet?

Thanks.

By the way, I'm sorry to say, but the search function on the forums here is not very good - searching (on the Product forum page) for posts related to the Product theme brings up anything but that, then wipes the search field so you cannot even try and narrow the search. Is there no way of only searching a particular forum (i.e. in this case the Product theme forum?)