Authorization issue not solved by Adobe instructions

I checked out a book from my local library in EPub format. It appears in my ADE app on my MacBook. I can drag it from ADE to my connected E-Reader. However, when I try to open the book on the E-Reader I get the message that "Your eReader is not authorized to open this book. It is protected by DRM. Because you previously deauthorized your eReader you need to import using ADE." I have tried deauthorizing, reauthorizing, reinstalling. What should I do?