Probleme pour mettre a jour Debian 5.0 vers Debian 6.0

Lors du passage de Debian 5.0 Lenny a Debian 6.0 Squeeze
Erreur d'update

Reading package lists... Done
W: GPG error: http://backports.debian.org squeeze-backports Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY AED4B06F473041FA
W: GPG error: http://security.debian.org squeeze/updates Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY AED4B06F473041FA
W: GPG error: http://ftp.us.debian.org squeeze Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY AED4B06F473041FA
W: GPG error: http://ftp.us.debian.org squeeze-proposed-updates Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY AED4B06F473041FA
W: You may want to run apt-get update to correct these problems


solution
Importer la cle publique depuis internet.

apt-key adv --recv-keys --keyserver subkeys.pgp.net AED4B06F473041FA; gpg --export --armor AED4B06F473041FA | apt-key add -