hmm, the problem maybe with varnish. I turned varnish off and now the plugin is working at least at the backend, when i cancel a booking after 60s it will be canceled. But frontend still not working I wonder why. I checked all permissions and restrictions but still dont know where to look for. I asked the server provider to look into it as well. Still the plugin is taking a long time to work, it would be nice to include a work in progress animation esp at the frontend.