Error Validation Custom Rule

Hello.

I have a problem when adding the following rule it always shows me error. What this rule does is check if a Spanish DNI is correct or not.

I don't know if the name of "Rule name" and "Error message" are correctly inserted

I have tried this code on other sites and it works for me but not here.

What can be happening?

https://drive.google.com/file/d/1FIUGcCa7lClHu5oH7C5Axx2gy4kJlmaf/view?usp=sharing