iCal calendar

[tseinc]

Good day,
So as a happy zimbra 4.5 user, I have been trying to use the calendar feature, I have a separate calendar account that has it's calendar shared with all our users. However, in trying to use lightening or sunbird with iCal, I am having trouble.
I have read all the posts about the problems, and how it _should_ work. And for the first day, publishing calendars from lightening *did* work.
However the next day we only recieve the error:

"Publishing the calendar file failed
Status code: 500: Internal Server Error"

I don't really know what to do with that. So, for 4.5 open source ed. _should_ syncing calendars work? ... and if so, any ideas on what is wrong? Thanks,
Greg
---
Also, I am using thunderbird 2.0 and lightening .031 and I have tried many URLs for the calendar, but the one that worked for a day was:
(the shared calendar is called "calendar" :-))
https://oursever.com/home/calendar/Calendar

[jholder]

If there's something wrong, then the server's gonna log a stacktrace in the mailbox.log file.

Can you post that?

Thanks
john