[mlevin77]

I'm using De-DRM v5.1, either as the plug-in to Calibre or the standalone AppleScript. It seems to work for some of my files (.AZW files on my Mac version of Kindle - books that I own) but for others, it says

"Error: decryption unsuccessful: no valid pid found"

but I thought the instructions say you don't need a pid for files in Mac Kindle application. What am I doing wrong?