Oculus Controller isn't able to "click" but mouse is in preview

I’m working on a dialog situation where the user can choose between various answers (a little bit like the good old point-and-click adventures). All works fine in my experience except the user input in VR. In the preview of UE4 the answer button can be clicked (with the mouse), but if I’m launching the experience on my Oculus Go, I can only watch around. Nothing is clickable. Not even the pointer of the Oculus Controller is working.

In the Event Graph of my Oculus Pawn, I added the Oculus Controller.

In the Event Graph of the Dialog WIndow I used the “Get Player Controller” function.

I surely did something really easy wrong, but at the moment I don’t know what to do.
Also, I could give further informations or screenshots, if it helps.

Thanks for helping!