Presented stimulus in psychopy staircase experiment does not change

Question

I just started using Psychopy in order to create my first adaptive staircase experiment. I tried to set up the experiment by using the Builder interface. The loop type I'm using is the staircase, not the interleaved staircase.

In the experiment, I would like to change the contrast of the image according to the participants response.

I've already designed the experiment so far that I can present the start stimulus to the participants, when the program runs. Also, the participant can respond. But the problem is, that my stimulus does not change at all after a participant responded. I've tried so many things to fix that, starting from inserting every possible stimulus manually, coding it according to the tutorial of Yentl de Kloe, but nothing is working - the simulus remains unchanged which leads to the result that the experiment runs forever, if I dont cancel it manually.

Is there anyone, who can tell me a simple (for a beginner understandable), but detailed solution how to solve this problem within the Psychopy Builder?

Thank you in advance!

Experimental Structure Staircase Loop