[Mailman-Users] RuntimeError: command failed: /usr/sbin/postalias

I can access Mailman webpages just fine; however, after I fill in the new list info and hit submit I get an error message ("Bug in Mailman version 2.1.5 We're sorry, we hit a bug!.") Also, it seems that no emails can be sent or received trough the list.

I've tried to add in mm_cfg.py the following two lines to solve the problem (see error log below) but this didn't help either.

POSTFIX_ALIAS_CMD = /usr/sbin/postalias POSTFIX_MAP_CMD = /usr/sbin/postmap

Python 2.3.5, Mailman 2.1.5, Postfix 2.1.5, Apache 2.0.54

Relevant error logs: admin(3095): [----- Traceback ------] admin(3095): RuntimeError: command failed: /usr/sbin/postalias /var/lib/mailman/data/aliases (status: 1, Operation not permitted)