I followed the documentation for enabling automatic upgrades in Ubuntu servers, but it's not really updating anything at all.

My /etc/apt/apt.conf.d/50unattended-upgrades looks almost like the default.

// Automatically upgrade packages from these (origin, archive) pairs
Unattended-Upgrade::Allowed-Origins {
        "Ubuntu karmic-security";
        "Ubuntu karmic-updates";
};

// List of packages to not update
Unattended-Upgrade::Package-Blacklist {
//      "vim";
//      "libc6";
//      "libc6-dev";
//      "libc6-i686";
};

// Send email to this address for problems or packages upgrades
// If empty or unset then no email is sent, make sure that you
// have a working mail setup on your system. The package 'mailx'
// must be installed or anything that provides /usr/bin/mail.
Unattended-Upgrade::Mail "[email protected]";


// Automatically reboot *WITHOUT CONFIRMATION* if a 
// the file /var/run/reboot-required is found after the upgrade 
//Unattended-Upgrade::Automatic-Reboot "false";

The directory /var/log/unattended-upgrades/ is empty. Running /etc/init.d/unattended-upgrades start is not very nice:

root@mozart:~# /etc/init.d/unattended-upgrades start
Checking for running unattended-upgrades: root@mozart:~#

Something seems to be broken, but I'm not sure why.

I have pending updates and they are not being applied:

root@mozart:~# aptitude safe-upgrade
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Reading extended state information      
Initializing package states... Done
The following packages will be upgraded:
  linux-libc-dev 
1 packages upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
Need to get 0B/743kB of archives. After unpacking 4096B will be used.
Do you want to continue? [Y/n/?]

In all the servers I have, unattended upgrades seems to have been disabled:

root@mozart:~# apt-config shell UnattendedUpgradeInterval APT::Periodic::Unattended-Upgrade
root@mozart:~#

Any ideas what am I missing?