HTML Form not submitting – PHP [closed]

For my website I have a contact form but when I try to submit the form, nothing happens.
I checked other answers on this webiste but I can’t seem to find the issue. The button does something, because when I try to submit with the fields not populated properly, I get the warning messages.

My Form:

<section class="contact-section">
    <div class="container">
        <div class="row">
            <div class="col-12">
                <h2 class="contact-title">Get in Touch</h2>
            </div>
            <div class="col-lg-8">
                <form class="form-contact contact_form" action="contact_process.php" method="post" id="contactForm" novalidate="novalidate">
                    <div class="row">
                        <div class="col-12">
                            <div class="form-group">
                                <textarea class="form-control w-100" name="message" id="message" cols="30" rows="9" onfocus="this.placeholder = ''" onblur="this.placeholder = 'Bericht'" placeholder="Bericht"></textarea>
                            </div>
                        </div>
                        <div class="col-sm-6">
                            <div class="form-group">
                                <input class="form-control valid" name="name" id="name" type="text" onfocus="this.placeholder = ''" onblur="this.placeholder = 'Uw naam'" placeholder="Uw naam">
                            </div>
                        </div>
                        <div class="col-sm-6">
                            <div class="form-group">
                                <input class="form-control valid" name="email" id="email" type="email" onfocus="this.placeholder = ''" onblur="this.placeholder = 'Enter email address'" placeholder="Email">
                            </div>
                        </div>
                        <div class="col-12">
                            <div class="form-group">
                                <input class="form-control" name="subject" id="subject" type="text" onfocus="this.placeholder = ''" onblur="this.placeholder = 'Onderwerp'" placeholder="Onderwerp">
                            </div>
                        </div>
                    </div>
                    <div class="form-group mt-3">
                        <button type="submit" class="button button-contactForm boxed-btn">Verzenden</button>
                    </div>
                </form>
            </div>
            <div class="col-lg-3 offset-lg-1">
                <div class="media contact-info">
                    <span class="contact-info__icon"><i class="ti-home"></i></span>
                    <div class="media-body">
                        <h3>Lier, Belgie.</h3>
                        <p>Frederik Peltzerstraat 88 bus 101, 2500 Lier</p>
                    </div>
                </div>
                <div class="media contact-info">
                    <span class="contact-info__icon"><i class="ti-tablet"></i></span>
                    <div class="media-body">
                        <h3>+32 (0) 494 67 64 92</h3>
                    </div>
                </div>
                <div class="media contact-info">
                    <span class="contact-info__icon"><i class="ti-email"></i></span>
                    <div class="media-body">
                        <h3>[email protected]</h3>
                    </div>
                </div>
            </div>
        </div>
    </div>
</section>

And my PHP file:

<?php

$to = "[email protected]";
$from = $_REQUEST['email'];
$name = $_REQUEST['name'];
$subject = $_REQUEST['subject'];
$number = $_REQUEST['number'];
$cmessage = $_REQUEST['message'];

$headers = "From: $from";
$headers = "From: " . $from . "rn";
$headers .= "Reply-To: ". $from . "rn";
$headers .= "MIME-Version: 1.0rn";
$headers .= "Content-Type: text/html; charset=ISO-8859-1rn";

$subject = "You have a message from your Bitmap Photography.";

$logo = 'img/logo.png';
$link = '#';

$body = "<!DOCTYPE html><html lang='en'><head><meta charset='UTF-8'><title>Express Mail</title></head><body>";
$body .= "<table style='width: 100%;'>";
$body .= "<thead style='text-align: center;'><tr><td style='border:none;' colspan='2'>";
$body .= "<a href='{$link}'><img src='{$logo}' alt=''></a><br><br>";
$body .= "</td></tr></thead><tbody><tr>";
$body .= "<td style='border:none;'><strong>Name:</strong> {$name}</td>";
$body .= "<td style='border:none;'><strong>Email:</strong> {$from}</td>";
$body .= "</tr>";
$body .= "<tr><td style='border:none;'><strong>Subject:</strong> {$csubject}</td></tr>";
$body .= "<tr><td></td></tr>";
$body .= "<tr><td colspan='2' style='border:none;'>{$cmessage}</td></tr>";
$body .= "</tbody></table>";
$body .= "</body></html>";

$send = mail($to, $subject, $body, $headers);

?>

If anybody could help that would be greatly appreciated!