[blitzkreig]

@iggy_grey:

Had same problem here. I found I could import them in the Windows version of Calibre but not the Linux version. Linux version refused to recognize any of the plugin zip files for some reason. Copying the plugin files directly to the plugin directory also failed.

What worked was to import the files into Calibre on Windows, then copy the files to the plugin directory in Linux. When Calibre on Windows imports them it renames the files. It doesn't modify the files, as confirmed by checking the MD5 hash.

As an alternative, you should be able to manually rename the files and then copy them to the plugin directory in Linux. Calibre on Linux still won't import the renamed files, but it will use them if manually placed in the plugin directory. The names of the plugin files on my system after import in Windows are:

eReader PDB 2 PML.zip
Ignoble Epub DeDRM.zip
Inept Epub DeDRM.zip
Inept PDF DeDRM.zip
K4PC, K4Mac, Kindle Mobi and Topaz DeDRM.zip

My Calibre versions...
Windows: 0.8.30
Linux: 0.8.8

Good luck!

EDIT: I just went back and read that you're using v0.8.30, so I suppose it's the Windows version. My advice may be useless in this case, except to say.... Make sure you unzip the downloaded .7z archive, but DO NOT unzip the individual .zip files inside. It's those individual files you need to import into Calibre.