[Mailman-Users] genaliases

[esteve serra clavera]

hi all,
i'm newbie on mailman ;)
i've already installed mailman after postfix. while trying to set up
mail lists accounts, i'm unable to link those with postfix trough
genaliases because it doens't exists [!]. i really don't know why i
don't have that program. i tested 2.0.11 and 2.1.4 and neither on each
genaliases seems to appear.
how can i tell postfix to give account admin to mailman , then?
thanks in advance!