How can I use Availability Panel in Calendar? There is an item named Availability Panel in Calendar:



When I open it this message is shown:


  This calendar does not support availability.


What kinds of calendars are supported for calculating availability? I have personal calendars in Calendar with recurring events that none of them work with Availability Panel.
On BusyMac there is an article about that. The Availability Panel is supported by e.g.:


Exchange and Office 365
Fruux
OS X Calendar Server
Kerio
Zimbra


and not supported by e.g. iCloud, Google Calendar, Yahoo, Communigate, Beehive.