"ERROR DIALOG, user not activated"

I just downloaded 2 EPUB books from my local library.  I successfully moved them into ADE.  I dragged them to my Nook.  They are showing up in my Nook library but when I try to open them I get the above message.  I even tried one of your sample books to make sure I didn't miss a step but got the same results.  What did I do to get this error message? How can I fix it so I can access these books?