Hi Henk, not sure which version or easyTravel you are using. I have just looked at our demo.live environment and it is working:
So best would be to open a support ticket in order to look at your tenant and check what's going on.
You should disable monitoring of launcher (com.dynatrace.easytravel.launcher.jar easyTravel (x*)) and weblauncher (com.dynatrace.easytravel.weblauncher.jar easytravel-*-x*) processes. Otherwise there will be no connection between application and services.