Is this just the one book, or a general problem?
Have you managed to copy any books to the Kobo and read them?
Have you managed to copy any DRM books to the Kobo and read them?
Are the computer and the kobo both properly authorized with your Adobe ID?
A couple of people have recently reported problems somehwat like yours, which they resolved with a factory reset of the Kobo.
Don't forget to back up any books on it first.