Only the tab "units" are displayed

For the time I use the version 2.3.1 of Event Calendar / Scheduler for WordPress.

In the backend of WordPress, I can deterministically mine which tabs are displayed above the calendar and which tab is the default mode. And I can choose between the following:

day
week
month
agenda
year

But I do not want to choose it, I will only the tab “units” are displayed. How do I get to work?

If i do not hook are not to see any rider,
but the standard mode I have to make a choice