I'm using the latest version of Calibre, and I have the tools from Apprentice Alf's blog (
here) downloaded and installed.
Tonight I downloaded a book in AZW4 format. I'd like to change that to PDF or epub so I can read it on my iBooks app. I downloaded and successfully installed KindleUnpack.
When I select the book, and click the KindleUnpack button along the toolbar, there's a red lock and the menu is greyed out. Now, in the previous response to someone else a few pages back, your instruction was to download the DRM removal tool - but I've already done that, I use those tools regularly. What else could be going wrong?