[horde] No Users Administration?

[Rob Brandt]

I'm wanting to learn about how the permissions system works for Users/Groups. 
I'm using  a HEAD snapshot from July 2nd.  I'm using SQL for preferences and
other data storage, and authenticating with imap.

When I go to Administration: Users: I get the following message:

Adding users is disabled.
Your authentication backend does not support adding users, or the feature has
been disabled for some other reason.

Listing users is disabled.
Your authentication backend does not support listing users, or the feature has
been disabled for some other reason.

I've looked through my conf.php, prefs.php and registry.php to find references
to enabling/disabling this, but can't find any.  Hints?

TIA

Rob