I'm trying to add on the Coupon Cabin Sidekick but when I go to the link at Coupon Cabin, they say to: Click the "Add to Firefox" button on the Mozilla Add-ons site. When I use Coupon Cabin's link for "Mozilla Add-ons site" it takes me to https://addons.mozilla.org/en-US/firefox/addon/couponcabin/ and the message on that link says, "Oops! We can’t find that page" so I did a search for Coupon Cabin add-on in Add-Ons and nothing for Coupon Cabin. What am I doing wrong? I have it on my laptop but can't seem to add it on to my new desktop pc.