I don't know where they are, but I can tell you why at least. Staples made a decision a couple of months ago that they didn't want to drop most of their affiliates but they wanted to set everyone at a 0% commission rate during the back to school season. Apparently it was a cost cutting measure. They did allow some sites to continue to get paid, but not very many and no one will say who.
They still send out emails every month asking us to post their banners for free on our sites, but you won't see most webmasters doing it when they are getting paid from all of the other office supply stores.