apt-get update doesn't

[Oliver Schoett <schoett@muc.de>]

I have made a tiny local subtree of the slink distribution to play
with mozilla.  With dpkg-scanpackages, I have made my own Packages
file and pointed apt to it. /etc/apt/sources.list has the single entry

   deb file:/home/local/mirror/debian slink main

apt-get update seems to get the Packages
file, but apt-get upgrade just reports

   Updating package status cache...done
   Checking system integrity...ok
   0 packages upgraded, 0 newly installed, 0 to remove and 0 not upgraded.

However, my mirror contains newer packages than the ones on my system
(libstdc++2.9, lesstifg, lesstifg-dev).

Here is my mirror tree (/home/local/mirror/debian):

    411026 Sep  9 13:52 dists/slink/main/binary-i386/admin/apt_0.1.6.deb
        96 Jul 12 13:09 dists/slink/main/binary-i386/Release
      1609 Sep 26 19:56 dists/slink/main/binary-i386/Packages.gz
   3158562 Sep 13 13:52 dists/slink/main/binary-i386/web/mozilla_19980904-1.deb
     95172 Sep 22 13:53 dists/slink/main/binary-i386/base/libstdc++2.9_2.91.57-3.deb
    561382 Sep 20 13:52 dists/slink/main/binary-i386/libs/lesstifg_0.86.5-1.deb
     98472 Sep 20 13:52 dists/slink/main/binary-i386/devel/lesstifg-dev_0.86.5-1.deb

The package info is recorded correctly in the file
/var/state/apt/lists/home_local_mirror_debian_dists_slink_main_binary-i386_Packages

The package versions on my system are:

   apt            0.1.6
   lesstifg       1:0.86.0-2
   lesstifg-dev   1:0.86.0-2
   libstdc++2.9   2.91.57-1
   mozilla        19980904-1

Trying another sources.list line gave the same result:

   deb file:/home/local/mirror/debian dists/slink/main/binary-$(ARCH)/

What have I done wrong, why does apt not work?

-- 
Oliver Schoett      <schoett@muc.de>