my kobo will not allow me to read the book I have downloaded

[Naomi_Eng]

Can anyone help me with the following.  I have borrowed an ebook from the library, downloaded it, transferred from ADE to my Kobo mini and authorised both the computer and the Kobo, but I can't open it to read on my ereader.  I get a message saying that the document is protected by ADE and is not currently authorised,  I thought I'd done everything - what have I missed? Any help most appreciated.  Thanks

[aliceDePalace]

More than 4 years later and the same problem occurs. It is the same for me and my Kobo Aura. I have deauthorized and reauthorized the device and the computer at least 20 times, uninstalled ADE, nothing worked. 

This is very frustrating.