Now the timetable works
Thank you!
Summary (for all who have the same problem)
1. Activate the function 'timetable' in the device you want to switch.
2. In the input fields for for the days just input the number of the timetable you want to use.
There are 10 timetables available.
3. Activate the timetable checkbox.
4. Edit the timetable. Be sure to select the right timetable number.
5. And Voila, all works fine.