[Mailman-Users] debian exim4 and mailman pipe_transport unset

[kick]

hello,
ive got a setup problem,

im using debian sarge 2.6 kernel and exim4
my mailman is able to take subscriptions from the website and confirm 
then no problem,
i get new member notifications and unsubscribes etc
the problem is no posts are getting through

when i run  exim4 -bt mailman@*******o
i get this

R: system_aliases for mailman@*******o
mailman@**********o -> |/var/lib/mailman/mail/mailman post mailman
*** Error in setting up pipe, file, or autoreply:
pipe_transport unset in system_aliases router

ive read the archives as deeply as i can and googled for ages ..but i 
think my brain is getting tired and if ive missed an obviouse answer im 
sorry,
my exim.conf seems to be /etc/exim4/update-exim4.conf.conf
(is there a command that will tell me exactly what the config file is???)
ive setup mailman in /etc/aliases
although i understand this may not be necessary
(will it harm it?)
ive also followed this http://www.tectonic.co.za/view.php?id=538


thanks in advance :)