upgrade error 8.01 > 8.1

[iben]

hi,
i try to upgrade my plesk from 8.01 to 8.1 but after two days, i'm still in 8.01 and the updater panel seems to be broken :

AutoInstallerManager::getAutoInstaller() failed: AutoInstallerManager::_autoInstallerCall() failed: autoinstaller failed: Empty error message from utility.
 
0: /opt/psa/admin/plib/common_func.php3:169
    psaerror(string 'AutoInstallerManager::getAutoInstaller() failed: AutoInstallerManager::_autoInstallerCall() failed: autoinstaller failed: Empty error message from utility.')
1: /opt/psa/admin/htdocs/server/autoinstaller_releases.php:26

what's wrong ? Thks