How can I activate books with adobe digital editions when I get an error?

I have a nook glowlight plus and I downloaded adobe digital editions to my mac so I could transfer local public library books to my nook.

The books show up on my nook but when I try and open them I get an error message that says "error opening book.  This book is not activated for current ADE users".  When I contact Barns and Noble they say its an Adobe problem.  I can open the book on my computer so its not a library problem.  How can I fix this problem?

Thanks so much for your help

Sydney