[Dovecot] doveadm director map : User listing returned failure

[Ramón Frontera]

Hello
we are running Dovecot 2.1.9.
We have 2 proxies with director and 4 mail servers.
We have the user information in a LDAP.

I try to do:
# doveadm director map
doveadm(root): Error: User listing returned failure
doveadm(root): Error: user listing failed
user                                                mail server ip expire time        
<unknown>                                             x.x.x.x    2012-09-12 10:52:17
<unknown>                                             x.x.x.x    2012-09-12 10:55:53

in the dovecot log i have found:

dovecot: auth: Error: Trying to iterate users, but userdbs don't support it


What can I do to solve this problem?
Thanks in advance. 

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  Ramon Frontera Gallardo
  Universitat de les Illes Balears