Install package from stable on old stable on debian

Question

I'm running Debian oldstable (Lenny) and upgrade is not in plan for the next two months at least.

I need to install the stable version of the erlang package, available at the stable (Squeeze) repos.

I did the following:

• Added the squeeze repositories to my source.list
• Added the 'apt.conf' file to /etc/apt with the following content:

APT::Default-Release "lenny";

• Added the 'preferences' file to /etc/apt with the following content:

Package: *

Pin: release a=lenny

Pin-Priority: 700

Package: *

Pin: release a=squeeze

Pin-Priority: 650

(added extra identation because someway the editor is not respecting my line breaks)

I don't want apt to install squeeze packages by default, but only when requested with commands like: apt-get install -t squeeze package

But apt is not respecting this, and IS trying to install the squeeze packages. What am i doing wrong?