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?