After setting up zimbra server, I've created accounts and forced them to change password at first time of login.

The problem is that after they've chaged their password, they still can login to server but nothing's displayed on their web page. So I try to test =>
1. Login by using URL : http://<hostname> e.g. :
The result is same to my end users (Nothing's displayed)
2. Login by using URL : http://<IP> e.g. :
After changed password for first time login, Inbox is opened successfully.