Hmm .. since its relevant only to my domain, I dont think it would be helpful.
But I will try to give some detail.
My zimbra is at
zimbra.abc.xyz.com
and my email is:
zrox@zimbra.abc.xyz.com and
zrox@abc.xyz.com
ldapsearch returns the string as
dn: uid=zrox,ou=people,dc=zimbra,dc=abc,dc=xyz,dc=com
So I tried
dc=zimbra,dc=abc,dc=xyz,dc=com
It did not work. Then today I changed it to
dc=abc,dc=xyz,dc=com
It worked.