Have you also authorized the Kobo eReader with the same Adobe ID as your copy of ADE?
Thanks sjpt, this of course has to be clarified, the user name for Kobo is my email address, this is how I communicate with Kobo. The Adobe ID is also my email address, if I click on help and check the authorisation, I am told that the Adobe ID is authorised. As they are the same they should work, one would think.
It may be that you need a little more: not sure about the user name for Kobo is my email address, this is how I communicate with Kobo.
That might be a Kobo specific knowledge of your email, and not have got through to the Adobe DRM part of the Kobo necessary for reading DRM eBooks.
Also, the Help on the authorization may only be telling you about the Adobe authorization of ADE, and not of the device.
Lots of mays and mights above, but try ....
When the Kobo is plugged into to computer with ADE running, the Kobo should show in the left hand panel.
Then run 'menu/Help/Authorize Device' (menu/Library/Authorize Device on older v1.7.2) to make sure the Adobe registration has been passed to the Kobo.
Thanks for your time sjpt, I sign on to my Kobo using my email address, my Adobe ID is also my email address. I tried your suggestion, still end up with a blacked out unopenable book in my Kobo. I am going to can this for now, too much of a time user! I will let you know if later on I can make this combination work. Cheers!