Trigger an auto reply depending on public holiday

I am tasked with setting up auto-reply-functions for our Zammad-system. We’re already using a trigger set up like this:
CONDITIONS
Action is created
State is not closed
Type is email
Sender is Customer
Group is (the group we have created for one of our products)
EXECUTE CHANGES ON OBJECTS
Email, public, set to no receiver in particular.

This trigger seems to work well, and I receive auto-mails when writing to the mail-address connected to the trigger/the group in question.

I set up another trigger just like it, but without getting any auto-mail back. I set up an alternative calendar for this purpose, one that has opening hours from 0:00 to 0:01, and started the new trigger with the condition “Calendar is not in working time” (and then I chose the newly created calendar).

The trigger should be triggered when a customer sends a mail to us on a national public holiday, but shouldn’t be triggered when our support opening hours are over, and neither in the weekends.

What is it that I am doing wrong?