Do you have @me.com and @mac.com emails? I had the the problem you describe with these. Most other Apple services allow you to use both domains interchangeably for your userid, but when I tried to publish my ibook, it would only recognize one of them as valid.
is there anyone out there who can assist with this question?
I have tried, @mac,@me,@icloud sign in with no success.
Checked my Apple ID profile, signed in to iCloud with both 2Mac and @me.cold reoot, warm reboot.
I have contacted Apple but no response .
Still can't get to 2nd base with publishing. Not much use if there is a bug.
any suggestions, please and thanks.