I can't read a book (epub)

I bought and downloaded a book which has a protection. I could read it. All was OK.

Then I update Adobes Digital Edition (version 4.5.11). And now, I can't read anymore my book. Message : "Impossible to open <book>.epub. Erros detected on this element <book>". And no more information.

I try to download again my book. But, read it, is impossible : same message.

What can I do to read again my book ?