[TYPO3-calendar] No events in ICS calendar

[Ralf Heydenreich]

Hi all,
I've configured cal with multiple calendars. One of them is a normal
calendar which works as expected (list view shows all expected events).
The second calendar is an imported ICS file. I think this file is valid
since I've imported it successfully into Mozilla Thunderbird
(Lightning). But in the list view of my page there are no events
displayed for this calendar. I've used the standard templates which are
delivered with the cal extension. Is there anything additionally to
configure for ICS list view?

TIA,
Ralf.