Qt installer framework connect to NextButton

Question

I try to connect the NextButton of the page TargetDirectory with a function:

widget.findChild("NextButton").clicked.connect(this, func);

But the problem is that findChild returns 0. I tried

widget.findChild("TargetDirectoryLineEdit").textChanged.connect(this, func);

and this works. Does anyone know how to catch the clicked signal of the next button?

Thank you.