CalDAV Failure on Thunderbird/Lightening

[3333 at tutanota.de]

I'm an end user, not an IT person. Let me know if I'm in the wrong space 
asking questions. I've failed for a month to can't get mykolab.ch CalDAV set 
up on Thunderbird 31.0. w Lightening 3.3.1.

I've tried the generic "human readable" link 
https://caldav.mykolab.com/calendars/myname@mykolab.com/Calendar and the link 
generated by the calendar at mykolab.com. I've tried installing as a calendar 
"on the network" both with and without offline support. Both ways result in 
the calenders immediately going offline by unchecking themselves.

At one point I was able to sync with Kontact but I need to set up Thunderbird 
for myself and potential users.  In case its relevant, my webmail calender 
has had issues which remain unresolved. For example: 800+ events disappeared 
from the webmail interface last week. It seems I should still be able to 
connect via Lightening, despite the previous loss of data.

Kindly point me elsewhere for support if I'm in the wrong group.

Thanks,
Vladi




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