This seems to have started recently. It worked in the past.
I check out a book from the library via overdrive. Open on mac in Adobe Digital Editions - this sees my nook and transfers the file without error. The book will open on the mac in Adobe.
I see the book on my Nook. I go to open it, the screen flashes, but nothing opens. No error message either.
Solved it with help from another thread.
Uninstall Adobe Digital Editions 4 and install v 3. Now it all works again.