Language problem in `date` with cron

[Guillaume]

Hi,
i setup a cron job sending a mail to a user every days, with this command :
echo "message body" | mail -s "`date +%A %d %B %Y` subject" user at domain

But the day of the week is displayed in English and not in french in
the subject line (%A). I try to use environemental  var like LANG=FR
of LANG=FR_fr in the script, but the day is still shown in English.
Any idea how tho change this behaviour ?
Thanks.

-- 
Guillaume