iCal CalDav blank calendar

[jbhardman]

We are using the Network Edition Zimbra server. I want to use iCal on my mac. I open iCal and go into the prefs. I create a new account with all of my server and login info. Everything goes fine, and I see the new calendars show up in my left hand column. One named "Calendar" and one named "Tasks". The problem is that they are both blank. When I go into the Zimbra web client I see all of my appointments right away.

I have a Macbook with OS X 10.5.7. One thing to note is I have installed Safari 4.

Does anyone else have this problem?