I'm trying to login Zimbra using external LDAP which is openLDAP. When I test login authentication using Zimbra Administration console, test is successful like this:

test_ok.png

But I can't login Zimbra using Web client. Getting an error like this:

Code:
The username or password is incorrect. Verify that CAPS LOCK is not on, and then retype the current username and password.
Authentication Settings
Code:
Authentication mechanism: External LDAP
LDAP bind DN template: uid=%u,ou=staff,dc=ibu,dc=edu,dc=tr
LDAP URL:	ldap://194.27.225.102:389/
Enable StartTLS:	
LDAP filter:	 uid=%u
LDAP search base: ou=staff,dc=ibu,dc=edu,dc=tr
Use DN/Password to bind to external server: Yes
Bind DN: cn=admin,dc=ibu,dc=edu,dc=tr