Plesk and Mailman Problems...

[sally27]

i install the plesk 8.0.1
the installation it's ok but i have a problem with the mailman.
when i execute the start command i received this error.

service mailman start
Starting mailman: Traceback (most recent call last):
File "/usr/lib/mailman/bin/mailmanctl", line 105, in ?
ImportError: No module named grp
[FAILED]

what's happen? i use fedora 4

thanks all ***