[Dovecot] questions about SETQUOTA

hi,

i tried to setup my configuration to use the SETQUOTA command but the
only thing i got is:

3 setquota "User quota" (storage 12345) 3 OK Setquota completed.

but nothing is changed in database.

i modified the password_query and the user_query to return the admin
and userdb_admin field, both set to y.

all other changes that are done are like in the wiki
http://wiki2.dovecot.org/Quota/Configuration

enabling debug doesn't show anything in debug.log