The mailing list for listmasters using Sympa

[Simone Dal Maso <address@concealed>]

Hello,
installed new version on Debian, 6.01.23.
I'm using postfix as mail server.
Now, when I create a new list from the wws interface, the list is 
created but I have an error and looking into sympa.log it says:
 May 24 12:06:37 localhost wwsympa[10871]: err admin::install_aliases() 
admin::install_aliases : Unable to run newaliases 



I really don't know what to do, I ran newaliases manually but is not the 
solution I think!
Ideas?