How to fix Language error

["abdelkader belahcene" <abelahcene@gmail.com>]

Hi all,
each time I install a package I get the error ( or warning) about the
Lang envir  variables:

After unpacking 14.8MB of additional disk space will be used.
Do you want to continue [Y/n]? y
WARNING: The following packages cannot be authenticated!
  python2.5-minimal python2.5
Install these packages without verification [y/N]? y

perl: warning: Setting locale failed.
perl: warning: Please check that your locale settings:
        LANGUAGE = (unset),
        LC_ALL = (unset),
        LANG = "fr_FR.UTF-8"
    are supported and installed on your system.
perl: warning: Falling back to the standard locale ("C").


the file is :  cat /etc/environment
LANG="fr_FR.UTF-8"

Do I need to add something there or elsewhere

thanks a lot
best regards
bela