Add booking isn’t working anymore

Hello,

I use the add booking page to add bookings that are being made by phone or mail. For some reason, the page suddenly disappeared.

When I click on add booking an almost empty page is showing. The only content on it is:

”
This page is for adding bookings from the administration area. The captcha and payment process are disabled in order to allow the website manager easily adding bookings.

Administrator options
[] Send notification emails for this booking
”

So an info text and a checkbox. But no other form options or a submit button.

Does anyone know what could cause this problem?

Thanks for the help in advance.

Kind regards,
Merijn