"This book has been returned. Loan not on record." - I have a Mac

**I have a Mac

Nook paper backlit

When I attempt to put a library book on my Nook I get one of two messages:

"Error Dialog- This book has been returned. Loan not on record." - .epub

"This NOOK cannot read this file. It may be an unsupported format." - .acsm

My Nook only supports .epub however, I wanted you to be aware of what happens when attempting to use an .acsm.

I tried installing ADE 3.0 per previous posts however, it's no longer supported with the IOS I have. I had to download ADE 4.5.11 in order for ADE to open. 

I have two books I am trying to read. I returned one of the books and rechecked it out, that didn't work. 

My Nook and compture are both authorized under the same account.