Issue with Digital Edition

After transferring an eBook (borrowed from the public library) using Adobe Digital Edition to my Kobo eReader, (from my computer), each time i try to open it I get:

"Oops! This document couldn't be opened. This document is protected by Adobe Digital Rights Management and is not currently authorized for use with your Adobe ID. Please sign in with authorized Adobe ID and try again".

I tried with different books, and Adobe verisions: 4.5.5, 4.3,  4.5.6. I erased authorization from both computer (in which the book is downloaded) and the Kobo device, and authorized again. Didn't help.

Any suggestions?

Thanks for your help,

HenryG