[SOLVED] Appointment invisible

[kwang]

I ran Zimbra 5.02 Open Source Edition and client on Firefox 2.0.0.12 ajax interface. As shown in the attachment 1, I can not see any appointments on Mar 14th in the calendar view. When I book a new appointment, I can see that my status is 'out of the office' on Mar 14th. Can anybody give me a hand to identify if this is a bug or a configuration problem?

[kwang]

Did not check the checkbox which is on the left pane.