Can't pin Wheezy on Linux Mint Debian Edition (LMDE)

Can't pin Wheezy on Linux Mint Debian Edition (LMDE)

I'd like to have your advice on yet another pinning problem that hit me recently. I've been through man apt_preferences several times, and I can't find anything wrong in what I did.
I was having kernel panics in Linux Mint Debian Edition (LMDE), when I decided that I wanted to use packages from Debian Wheezy to get a newer kernel that could fix them.
I decided to try with pinning. The plan was to add a deb source for wheezy, and pin it with a very small priority, so that Wheezy packages would be installed only if explicitly requested for. Then, I would install the kernel-image from Wheezy.
I added this source:
deb http://ftp.uninett.no/pub/linux/debian wheezy main contrib non-free
And this pin:
Explanation: Disable Wheezy
Package: *
Pin: origin ftp.uninett.no
Pin-Priority: 1
But didn't work. I tried several other approaches like:
Explanation: Disable Wheezy
Package: *
Pin:  release o=Debian,n=wheezy
Pin-Priority: 1
or even
Explanation: Disable Wheezy
Package: *
Pin:  release n=wheezy
Pin-Priority: 1
No matter what, and even with negative priorities, Wheezy packages still had the same priority (500) as the LMDE's, and they were preferred to LMDE's since they were newer.
Can you see anything that I missed so far?
Thanks in advance
-- bronto
PS: If you're interested in the specific panic problem, you can read the full story here