Unable to authorize Kobo Reader

I keep getting Activation server Error. code: E_adept_user_unknownhttp.//adeactivate.adobe.com/adept/activate Digital Editions encountered an error on activation server. To retry click Try Again button. I couldn't open books on my Kobo reader, so I deauthorized it and now can't re authorize. Just get the error message. I have the latest ADE 4.5.6 on a Win 7 computer.