I clicked on the link via the email announcing the promo that I had received. It auto-filled my info, and I submitted. The next page showed my terms, but asked me to click once more to register. I got distracted with work, and closed the browser before registering with the second click. When I went back to try again later, I got the same "is not recognized" error that several others here have cited. I'm wondering if the others who got this message had similarly aborted signup attempts - not necessarily closing the browser, but waiting a while (causing timeouts), broken internet connections (changing IP address), etc.? That could explain it for many, or maybe just in cases like mine. I can't think of another reason it would work the first time but then not 10 minutes later.