What is the message?
Have you authorized the Kobo?
There are bugs in ADE2.0 with certain ebook readers, especially with Overdrive library books. Try v1.7.2 instead.
Version 1.7.2, it is a little difficult to find, available on Adobe site for Windows and for Mac.
The forum software is sometimes corrupting the link above. There shouldn't be a blank in 'editio ns.html'. The following redirects to the same page: http://tinyurl.com/diged172