[Dovecot] quota and postfix virtual users

[gbotero at emailforall.no-ip.org]

hi everyone i have a mailserver working with postfix 2.5.1 vda and
virtual user with mysql and dovecot, everything is working fine but i want
to offer quota and i have a problem with that because the quota in
roundcube appear but calculate is wrong i need to delete the maildirsize
file to force to recalculate, what can i do??? in my dovecot i have imap{
quota imap_quota, in plugins section i have quota=maildir and trough the
file dovecot-sql.conf i have the select expression concat(...... as
quota_rule, thanks a lot, 

PD. sorry for my english im from south of
colombia - south america