Netlify form: There is no "Thank you" popup

Greetings to all!

I am a newbie in Netlify so I’ll appreciate the help and I apologize in advance if I posted in the wrong category or asked the question “wrong”.

Here is the issue:
I’ve seen some tutorials of how to use the netlify forms and it appears that I am doing everything correctly…maybe.

But the results in the tutorials are different. When the user “submits” the form they get the “thank you” popup, I don’t. May someone help?
Here is the form:

<!-- Contact Form Starts -->
            <div class="col-12 col-lg-8">
                <form method="post" name="contact-form" class="contactform" netlify>
                    <div class="contactform">
                        <div class="row">
                            <div class="col-12 col-md-4">
                                <input type="text" name="name" id="name" placeholder="YOUR NAME">
                            <div class="col-12 col-md-4">
                                <input type="email" name="email" id="email" placeholder="YOUR EMAIL">
                            <div class="col-12 col-md-4">
                                <input type="text" name="subject" id="subject" placeholder="YOUR SUBJECT">
                            <div class="col-12">
                                <textarea name="message" id="message" placeholder="YOUR MESSAGE"></textarea>
                                <input type="submit" name="submit" value="Send Message" class="btn primary"/>
                            <!-- <div class="col-12 form-message">
                                <span class="output_message text-center font-weight-600 text-uppercase"></span>
                            </div> -->
            <!-- Contact Form Ends -->

Thank you.

The form html looks normal to me. Could you please read this article about debugging steps, and if they don’t help you solve it, please answer the two questions at the end so we can see the form “live” to better advise?