It used to work fine before, but starting this week, seems like ZCO cannot sync the appointment I created in outlook to the Zimbra server. However, if I create the appoinmtne in Zimbra server, it can sync over to outlook. Other than this, task and mail seems can sync without any issue. Anyone have an idea on why outlook calendar cannot sync to Zimbra server? or know of any fix?

I am using ZCO 5.0.3 on Outlook 2007. While we are planning to upgrade to 5.0.5, we are not there yet.