apt.conf doesn't have effect anymore

["Dvorzhetsky" <dvorzhetsky@airpost.net>]

Hello,

I'm mainly using lenny, but I have as well sid and experimental
repositories in my sources.list. To give priority to lenny I use
apt.conf file. 

Every thing was fine until I decided to had a third party repository for
lenny. Unlike debian repositories, the version of debian is in the path,
it doesn't appear as an argument. I was concern that my apt.conf would
not work properly so I commented experimental and sid repos and renamed
apt.conf to apt.conf.bak. I installed what I wanted and stayed with an
exclusively lenny sources.list for a while. It was fine.

Now I don't use the third party repos anymore, I removed it from my
sources.list uncommented sid and experimental repos and got back my
apt.conf But even after apt-get update the other repos do not seams to
be taken in account by apt. apt-cache policy xxx only give me the lenny
version.

I can't remember to have run in any error during these apt process.

Anyone knows how to get back things as normal?

Cheers!