Caldav Calendar with organizing events

i´ve a calendar for my office on a nas. This caldav account works properly. So far so good.
In my mail account with emclient, i marked this calendar as standard calendar.

if i now make a new calendar entry and invite participants, no mail is sent to the invited participants. this seems to be related to the owner of the calendar account. This is not identical with my mail account.

Example: my mail account ist [email protected] and the caldav account is named oscar, so the
owner of the calendar is [email protected].

Switching the name of the caldav account leeds to [email protected].

If i make a new local calendar in emclient, then there a new entry and then invite participants, everything works fine, but i need to use my office calendar, because it ist open for my employees.

Do you have any suggestions?