How to use XPath query for an HTTP request output?

Hi,
I’m becoming mad, I’m definitely doing something wrong.

I have this simple scenario:

I get the html of the https://www.comune.palermo.it/novita/ordinanza-n-211-del-11022025/ page, the I try to run //h4 XPath query, but I have no output and strange error.

Below some screenshot with my settings.

What am I doing wrong?

Thank you