[Dovecot] CMUSieve with virtual users

[Guillaume HILT]

    Hi,

I'm using dovecot 1.1.7 on Gentoo with Postfix and PostfixAdmin to 
manage my virtual users.
I'm trying to use sieve (which has been compiled with Dovecot) but it 
doesn't work.

I added cmusieve in the lda protocol :
  mail_plugins = cmusieve
  mail_plugin_dir = /usr/lib/dovecot/lda

My maildir scheme is : /home/vmail/%d/%n/.maildir
The sieve file is in /home/vmail/%d/%n/.dovecot.sieve (i'm using the 
sieve variable in the plugin section).
I also tried in /home/vmail/%d/%n/.maildir/.dovecot.sieve.
Then I tried in /var/sieve-scripts/%u.sieve.
None of these solutions worked :x

I enabled all the debug options in dovecot, and i can't see anything 
about sieve in my logs.

I'm using the same configuration without virtual users on another server 
and it's working fine.
I'm out of ideas.

Could someone has managed to use sieve scripts with virtual users ?

Thanks :)

    Guillaume