I'm trying to access my GAL in Zimbra with an Mac OS X Address Book via LDAP.

I just want to do GAL searches.

I've tested a telnet connection to my server:
david@zimbra:$ telnet zimbra.mydomain.com 389
Trying 172.xx.xx.xx...
Connected to zimbra.mydomain.hk.
Escape character is '^]'.

In Mac OS X address book.
Add LDAP server:
* Name = Zimbra LDAP
* Hostname = <servername>
* Base DN = ou=people,dc=<mydomain>,dc=com

I also tried just this:
* Base DN = dc=com (

* Port = 389
* Bind DN = (leave blank)
* SSL = (leave unticked)

I tried without authentication and got no results.

Here's what I used with Authentication:
Authentication type: simple
User Name: uid=david,ou=people,dc=mydomain,dc=com
Password: ******

Still nothing.

When I search, I get no results. No errors, but no results either.

How can I debug this?
Where would I look on the client to see what the error might be?
Where would I look on the server to see if there is any log?