I'm using Debian Testing together with the Deb Multimedia (previously Debian Multimedia) repository for testing. I want to reduce the priority of the deb-multimedia packages so it only installs certain packages. I've tried with:

Package: *
Pin: release o="Unofficial Multimedia Packages"
Pin-Priority: 10

and

Package: *
Pin: origin "mirror.home-dn.net"
Pin-Priority: 10

But neither works, the packages still have the default priority (500).

The Release file from the repository looks like this:

Archive: testing
Version: None
Component: main
Origin: Unofficial Multimedia Packages
Label: Unofficial Multimedia Packages
Architecture: amd64

What am I doing wrong?

Edit: It worked when I used the Version information instead:

Package: *
Pin: release v=None
Pin-Priority: 10

But I still don't know the reason the other filters didn't work.