[Dovecot] Sieve and Namespace in dovecot 2.0.X

[Mauricio Tavares]

Based on what I read in
http://wiki2.dovecot.org/Pigeonhole/Sieve/Usage, if I have a namespace
defined as

tail conf.d/10-mail.conf

namespace inbox {
  inbox = yes
  location =
  prefix = INBOX.
  separator =.
  type = private

}

A global script like

cat /etc/dovecot/sieve/global-spam.sieve
require ["fileinto", "regex"];
# Must use regex here as 'contains' may not be valid, it erroneously
# moved:
# X-Spam-Status: No, score=-4.0 required=8.0 tests=ALL_TRUSTED,BAYES_00,
#       DCC_CHECK_NEGATIVE,HTML_MESSAGE,T_TM2_M_HEADER_IN_MSG,UNTRUSTED_Relay,
#       XM_SPF_Neutral autolearn=disabled version=3.2.5, No
#
# Due to the 'YES' in BAYES, let's just make sure YES is at the
# _beginning_ of X-Spam-Status, while ignoring anything past it.
#if header :regex "X-Spam-Status" "^[Yy][Ee][Ss].*" {
if header :matches "X-Spam-Status" "Yes*" {
  fileinto "INBOX.Spam";
  stop;
}

should put spam in bob/.Spam. But, I am getting an error message
stating that INBOX.Spam does not exist:

Oct 11 09:57:33 mail dovecot: lda(bob at domain.com): Error: sieve:
msgid=<0.0.0.71C.1CEC689A21CFF08.7068B7 at ip.aidolip.us>: failed to
store into mailbox 'INBOX.Spam': Mailbox doesn't exist: INBOX.Spam

How come?