Issues with Montana Template contact form

sorry to bother, but I have some trouble to get the contact form in Montana template work. I installed it on my webserver and changed the e-mail address in the “contact_process.php”
I tested and it shows correctly the validation messages set out in “contact.js” But if I enter everything so it should pass the validation, hit send, just nothing happens. No e-mail, no validation error, not deleting the form, just nothing.
As I am not super familiar with JS and Ajax, could you please indicate if I missed something in the set up or any ideas what could have went wrong.