Leslie,
thank you for answering that quickly!
I am uploading the projectfile to your offered link right now. It is a pretty messy project as it is the first one I am trying to do. You will find the described button on slide "2.8Auswertung" on the second additional layer "Ergebnis1". The very first slide of the course is of course the welcome slide. There, the most upper object is the mentioned text to check the variables.
I hope you can find the mistake I am doing.
And: I am just noticing that you will have to change one trigger on the basis-layer of 2.8 to make the layer Ergebnis1 visible when timeline starts on basis-layer. This one is right now set to Ergebnis4.