I'm using iCal on OS X Leopard and that has a feature to publish a calendar to a Webdav server (Calendar Menu/Publish...). However when I publish it to my Zimbra server (Open Source), it does not show up in the Zimbra webclient.

After some fiddling I found that the using the following URL in iCal as the 'Base URL' for publishing the calendar works...
https://<<server>>/dav/<<zimbra username>>

At least, iCal publishes it and provides a url when I can access the calendar at the Zimbra server (https://<<server>>/dav/<<zimbra username>>/Calendar.ics, I specified 'Calendar' as the 'Publish Calendar as' name in iCal). When I access this url directly from a browser I do get back an ics file. But it is not visible when I log into the Zimbra web client.

I also tried to pre-create a calendar in Zimba with the name 'Calendar' but that did not make a difference.

Any ideas what could be the problem?