pin priority in apt

Hi,

Despite the priority, I put in my /etc/apt/preferences

Package: *
Pin: origin ""
Pin-Priority: 999

Package: *
Pin: origin "localhost"
Pin-Priority: 995

Package: *
Pin: origin "ftp.fr.debian.org"
Pin-Priority: 501

When I install a package, it comes from ftp.fr.debian.org, even if this pacakge existe, in my locale repository??!!
Here is an example :

root@debian6:/opt/extra6Bis# apt-cache showpkg 9base
Package: 9base
Versions:
1:6-1 (/var/lib/apt/lists/localhost_extra6Bis_Packages) (/var/lib/apt/lists/ftp.fr.debian.org_debian_dists_squeeze_main_binary-i386_Packages)

while the installation comes from ftp.fr.debian.org here is :

/opt/extra6Bis# apt-get install 9base

Reading package lists... Done
Building dependency tree
Reading state information... Done
..................................
The following NEW packages will be installed:
9base
0 upgraded, 1 newly installed, 0 to remove and 449 not upgraded.
Need to get 1552 kB of archives.
After this operation, 4497 kB of additional disk space will be used.
Get:1 http://ftp.fr.debian.org/debian/ squeeze/main 9base i386 1:6-1 [1552 kB]

thanks for help
best regards

pin priority in apt_preferences