CalDAV on a Synology NAS

Hi,

Synology Firmware 3.2 now includes a CalDAV server. With Lightning I 
can order the calendars on that NAS without troubles.
If I would connect the CalDAV Calendar with Mulberry, then I got the 
following error message:

Could not read calendar:Not found
Account: Username
Calendar: calendarname

I catch the TCP Stream and I can see, that Mulberry recieve every 
calendar-entry. And then the stream ends and in Mulberry I see the 
error message above!

Could this be a bug in the CalDAV server or in Mulberry?

Thanks for any help.

Beat