[Dovecot] Virtual Folders

[qmail at top-consulting.net]

I have the following setup:

dovecot --version
1.2.10

namespace private {
   prefix = virtual.
   separator = .
   location = virtual:~/Maildir/virtual:INDEX=MEMORY
}

protocol imap {
mail_plugins = quota imap_quota fts fts_solr antispam virtual


#pwd
~/Maildir/virtual/all

#cat dovecot-virtual
*
all

The problem is that I can't access any of the virtual folders. Logging  
the IMAP conversation showed me this:


5ptq SELECT "virtual.all"
frdv IDLE
5ptq NO Mailbox doesn't exist: all (all)^M
+ idling^M
frdv OK Idle completed.^M

What am I doing wrong ?