Error trying to set Access Control on Caldav Calendars


I have been trying to set up Access Controls on a number of Caldav Calendars on our Server to allow the Calendars to be shared by other domain members. I have managed this on Mailbox folders in the same accounts, however every time I try to set Access Control on the Calendar folders - which otherwise are working fine -  I receive the following error:

[CalDAV / CardDAV] MailClient.Storage.Application.OperationException: Failed to set access control list. (Bad Request) 

Any pointers appreciated.

Thank you.