Every time I try to add a theme to MDM I get this error "File not a tar.gz or tar archive".
This happens to every theme I have tried to add. I even have unzipped the files and then re zipped to .tar or .tar.gz and I still cannot add any. I have also tried by unzipping the files and then manually adding them to /usr/share/mdm/themes. This does not work either as none of the files show up in Login Window Preferences.
I have made sure that the theme has MdmGreeterTheme.desktop as the desktop file and that it has MdmGreeterTheme as the desktop entry in MdmGreeterTheme.desktop.
Nothing seems to be working. Has anyone else experienced this or had any luck adding extra themes?