[gentoo-user] Can't mask a package

[Pupino]

Hello everybody,
i'm having troubles with the policykit package, and i've discovered
that the new version (0.92) has broken all APIs and this causes some
packages to not compile anymore (network manager in my case).
So i tried to mask it and keep the 0.9-r1 version instead, but with no result.
I've added it to /etc/portage/package.mask and tried this forms:
=sys-auth/policykit-0.92
>=sys-auth/policykit-0.92
and also
sys-auth/policykit-0.92
that should prenvet any version of it being merged, right?
none of those attempts worked for me, and emerge keeps trying to merge it...
i'm running a x86 system with no accept keywords set.
any ideas?

Thanks in advance.
Davide