enable du option in centos 5.2

[pine1455]

Hi,
I want to enable du option in ispconfig to get correct statictics of user mail directory.
so I just changed the config.inc.php according to this page : http://www.howtoforge.com/ispconfig-2.x-first-steps-p2
but still ispconfig can not run du command with sudo !!!
I got this error in /root/ispconfig/httpd/logs/error_log

du: `/var/www/web14/user/site.com_test/Maildir': Permission denied

any opinion?!!

[till]

Please reconfigure sudo as described in the first steps tutorial.