Sieve can't move messages in a public namespace

[Paolo]

Hello,

my dovecot version is 2.1.17
I've configured some public namespaces (config attached). When a mail 
arrives at a certain mail address, that mail is handled by dovecot lmtp 
server and a sieve script is executed that shuold move the message in 
one of the namespaces. This is the script:

require "fileinto";

if header :contains "From" "exam...@example.com" {
       fileinto :create "Cond-UFF_FORNITORI/CONTABILITA/Inviata";
}
else {
        fileinto :create "Cond-UFF_FORNITORI/CONTABILITA/Ricevuta";
}

The problem is that the sieve script fails with the error:

   sieve: info: started log at Jun 27 12:42:28.
   error: msgid=<c9154db4-ff68-52a3-2639-11f09f225...@fcr.re.it>: failed to 
store into mailbox 'Cond-UFF_FORNITORI/CONTABILITA/Ricevuta': Mailbox doesn't exist: 
Cond-UFF_FORNITORI/CONTABILITA/Ricevuta.

I double checked config, dovecot documentation, sieve documentation, 
ACL, filesystem paths, filesystem permissions, etc. etc. I'm pretty sure 
it's all right.
So why isn't sieve working?

Thanks if you bother to answer & Cheers

Paolo

# 2.1.17: /etc/dovecot/dovecot.conf
# OS: Linux 2.6.18-419.el5 x86_64 CentOS release 5.11 (Final) 
auth_gssapi_hostname = $ALL
auth_krb5_keytab = /etc/dovecot/dovecot.keytab
auth_mechanisms = gssapi plain
default_process_limit = 300
disable_plaintext_auth = no
hostname = my.mail.server
listen = *, [::]
login_greeting = IMAP/POP3 Server ready.
mail_gid = vmail
mail_location = maildir:~/Maildir
mail_max_userip_connections = 15
mail_plugins = acl listescape
mail_uid = vmail
managesieve_notify_capability = mailto
managesieve_sieve_capability = fileinto reject envelope encoded-character 
vacation subaddress comparator-i;ascii-numeric relational regex imap4flags copy 
include variables body enotify environment mailbox date ihave
namespace {
  location = 
maildir:/home/vmail/mailboxes/Condivise/DATIPHARM:INDEX=~/Cond-indexes/.DATIPHARM:CONTROL=~/Cond-control/.DATIPHARM
  prefix = Cond-DATIPHARM/
  separator = /
  subscriptions = no
  type = public
}
namespace {
  location = 
maildir:/home/vmail/mailboxes/Condivise/ADF:INDEX=~/Cond-indexes/.ADF:CONTROL=~/Cond-control/.ADF
  prefix = Cond-ADF/
  separator = /
  subscriptions = no
  type = public
}
namespace {
  location = 
maildir:/home/vmail/mailboxes/Condivise/CFO_FARMADATI:INDEX=~/Cond-indexes/.CFO:CONTROL=~/Cond-control/.CFO
  prefix = Cond-CFO_FARMADATI/
  separator = /
  subscriptions = no
  type = public
}
namespace {
  location = 
maildir:/home/vmail/mailboxes/Condivise/UFF_FORNITORI:INDEX=~/Cond-indexes/.UFF_FORNITORI:CONTROL=~/Cond-control/.UFF_FORNITORI
  prefix = Cond-UFF_FORNITORI/
  separator = /
  subscriptions = no
  type = public
}
namespace {
  list = children
  location = maildir:/home/vmail/mailboxes/%%n:INDEX=~/Cond-indexes/UTENTI/%%n
  prefix = Cond-UTENTI/%%n/
  separator = /
  subscriptions = no
  type = shared
}
namespace inbox {
  inbox = yes
  location = 
  prefix = 
  separator = /
  subscriptions = yes
  type = private
}
passdb {
  args = /etc/dovecot/conf.d/auth-ldap-passdb.conf.ext.FCR
  driver = ldap
}
plugin {
  acl = vfile
  acl_shared_dict = file:/home/vmail/mailboxes/shared-mailboxes.db
  sieve = ~/.dovecot.sieve
  sieve_before = 
}
postmaster_address = postmas...@fcr.re.it
service auth {
  unix_listener /var/spool/postfix/private/auth {
    group = postfix
    mode = 0660
    user = postfix
  }
  user = root
}
service imap-login {
  process_min_avail = 10
}
service imap {
  executable = imap
  vsz_limit = 256 M
}
service lmtp {
  executable = lmtp -L
  process_min_avail = 5
}
service pop3-login {
  process_min_avail = 10
}
service pop3 {
  executable = pop3
}
ssl_cert = </work/certs/mail_fcr_re_it-FCRCA.crt
ssl_key = </work/certs/mail_fcr_re_it-FCRCA.key
syslog_facility = local1
userdb {
  args = /etc/passwd
  driver = passwd-file
}
userdb {
  args = username_format=%n /etc/dovecot/test-users
  driver = passwd-file
}
userdb {
  args = uid=503 gid=503 home=/home/vmail/mailboxes/%n 
mail=maildir:/home/vmail/mailboxes/%n
  driver = static
}
userdb {
  driver = passwd
}
verbose_proctitle = yes
protocol imap {
  imap_client_workarounds = delay-newmail
  mail_plugins = acl listescape imap_acl
}
protocol pop3 {
  pop3_client_workarounds = outlook-no-nuls oe-ns-eoh
  pop3_uidl_format = %v.%u
}
protocol lda {
  hostname = mail.fcr.re.it
  mail_plugins = acl listescape sieve
  postmaster_address = postmas...@example.com
}
protocol lmtp {
  info_log_path = /var/log/dovecot-lmtp.log
  mail_plugins = acl listescape sieve
}