Sending out Event invitation

In the Calendar next to the first item “Events”, I see a red triangle with exclamation mark.
This
is probably related to the error that I can not send out invitations to an event (after saving the created event, the eM Client does not ask me whether to send out the invitation to the participants). The created event only appears in my Calender. Please help to solve it.

This means that there is some communication error with the calendar server. As a Pro License user, you should open a support ticket with eM Client and they will be able to assist you with solving this.

Gary Thank you for your reply. What our IT support did and really helped, was just to delete the current user account and re-create it. All emails, events etc. were synchronized with the server so I did not lost any data. My issue has been resolved this way.