[Help] Sieve error with imapflag

[Marco]

Hello,

  I would ask another little help. When I set this sieve script:

if true
{
     addflag "\\Flagged";
     keep;
}

I receive mails unflagged.

Other sieve rules work as expected.

If I want a working filter I have to set:

if true
{
     addflag "\\Flagged";
     fileinto "INBOX";
}


Could you help me? Many sieve clients make the first rule... it could  
be a bug?

This is my sieve:
"IMPLEMENTATION" "Cyrus timsieved v2.4.14-Invoca-RPM-2.4.14-1"
"SASL" "PLAIN"
"SIEVE" "comparator-i;ascii-numeric fileinto reject vacation imapflags  
notify envelope relational regex subaddress copy"
"UNAUTHENTICATE"

This problem occurs also with 2.4.13 version.

This is my imapd.conf:

===
configdirectory: /var/lib/imap
#partition-default: /dev/null
partition-maildata1: /maildata/comune.prova.it/maildata1
partition-maildata2: /maildata/uc.test.it/maildata1
partition-maildata3: /maildata/regione.piemonte.it/maildata1
partition-maildata4: /maildata/uc.csi.it/maildata1
partition-maildata5: /maildata/csi.it/maildata1
partition-maildatadm: /maildata/admin.invalid/maildatadm
#defaultpartition: default

metapartition_files: header index cache expunge squat
metapartition-maildata1: /metamaildata1
metapartition-maildata2: /metamaildata2
metapartition-maildata3: /metamaildata3
metapartition-maildata4: /metamaildata4
metapartition-maildata5: /metamaildata5
metapartition-maildatadm: /metamaildatadm

altnamespace: 0
serverinfo: on
admins: oxcyrus

annotation_definitions: /etc/annoIMAP.conf

sievedir: /var/lib/imap/sieve
postmaster: postmaster at regione.piemonte.it

sendmail: /usr/sbin/sendmail

fulldirhash: 1

hashimapspool: true
#sasl_auxprop_plugin: sasldb
sasl_pwcheck_method: saslauthd
sasl_mech_list: PLAIN
allowapop: 0


quotawarn: 80
normalizeuid: 1
syslog_prefix: cyrus
unixhierarchysep: 1
autocreatequota: 0
implicit_owner_rights: l
createonpost: 0
autosubscribe_all_sharedfolders: yes
expunge_days: 30
singleinstancestore: 1
defaultdomain: admin.invalid
improved_mboxlist_sort: 1
virtdomains: userid
quotadb: skiplist

allowusermoves: 1

====
I thank you very very much for every hints and helps!
Best Regards
Marco