I have a confirmation e-mail containing the tag #link_cancel#. The link in the e-mail points to the correct action:
https://www.vve-goudenleeuw.nl/?_ea-action=cancel&_ea-app=32&_ea-t=de56e27772e9b32ab54e38a351a8c269

Clicking this link causes the the message "Appointment is canceled" and the system sending a new confirmation e-mail (and not a cancellation e-mail).
The 'old' reservation is still available. The worker also receives a new reservation confirmation, with the default cancellation link. Clicking this link gives the message "Appointment can't be canceled". In the end I had to remove the appointment manually in the backend.

What could be wrong in my setup?

Thanks,
Theo