I googled and looked into all unkown issues on ubuntu forums but I can't figure out why a 10.04 LTS server won't detect the last LTS 12.04.1. I guess since 12.04 is a fresh dist, not much is reported for related issues

Here is what I did :

apt-get update

apt-get upgrade

apt-get install update-manager-core

it was already installed so no update for this package.

I checked : /etc/update-manager/release-upgrades

[DEFAULT]
# Default prompting behavior, valid options:
#
#  never  - Never check for a new release.
#  normal - Check to see if a new release is available.  If more than one new
#           release is found, the release upgrader will attempt to upgrade to
#           the release that immediately succeeds the currently-running
#           release.
#  lts    - Check to see if a new LTS release is available.  The upgrader
#           will attempt to upgrade to the first LTS release available after
#           the currently-running one.  Note that this option should not be
#           used if the currently-running release is not itself an LTS
#           release, since in that case the upgrader won't be able to
#           determine if a newer release is available.
Prompt=lts

I also checked my sourcelist before running apt-get : /etc/apt/sources.list

deb http://archive.ubuntu.com/ubuntu/ lucid main restricted universe multiverse
deb http://archive.ubuntu.com/ubuntu/ lucid-security main restricted universe multiverse
deb http://archive.ubuntu.com/ubuntu/ lucid-updates main restricted universe multiverse
deb http://security.ubuntu.com/ubuntu lucid-security main restricted
deb-src http://security.ubuntu.com/ubuntu lucid-security main restricted
deb http://security.ubuntu.com/ubuntu lucid-security universe
deb-src http://security.ubuntu.com/ubuntu lucid-security universe
deb http://security.ubuntu.com/ubuntu lucid-security multiverse
deb-src http://security.ubuntu.com/ubuntu lucid-security multiverse
# deb http://landscape.canonical.com/packages/hardy ./
# deb-src http://landscape.canonical.com/packages/hardy ./

and then following Ubuntu guide for Precise upgrade the command below should work :

root@xxxxxxxxx:/etc/apt# do-release-upgrade  -d
Checking for a new ubuntu release
No new release found

So am I missing something ?

The server was accessing outside through a proxy but I grant direct access to this server to avoid any Internet access problem or redirection but no clue...

Any help would be appreciated