Originally Posted by redbees
What version of the tools are you using? The most recent is v2.6. See the following thread in the Calibre plugin forum for more info, and you can ask questions there. I, too, am largely uninformed on this topic, but I do know that Amazon recently made changes to their DRM scheme that necessitated an update to the tools.
Here is the link. If it doesn't work go to: Calibre > Plugins > K4PC DeDRM Plugin
Yes, thanks, I had updated from an earlier version, but then the next day after I posted a newer one came out and that solved the problem. Now I see that there is even a 2.7 out so time to upgrade again.