Contact form that uses JS to validate and PHP to send not working

I would like help identifying the problem, I use a form that uses JS to validate and PHP to send, but it is not working. It works perfectly on other sites, however in that when clicking on SUBMIT (submit) it reloads page by adding a question mark to the end of the URL and the message is not sent. They follow form codes (HTML), validation (JS), and submission (PHP).

Form:

<form name="sentMessage" id="contactForm" novalidate>
    <div class="control-group form-group">
        <div class="controls form-group has-feedback">
            <label>Nome*</label>
            <input type="text" class="form-control" id="name" required data-validation-required-message="Por favor, insira seu nome.">
            <i class="fa fa-user form-control-feedback"></i>
            <p class="help-block"></p>
        </div>
    </div>

    <div class="control-group form-group">
        <div class="controls form-group has-feedback">
            <label>Empresa</label>
            <input type="tel" class="form-control" id="empresa">
            <i class="fa fa-building form-control-feedback"></i>
        </div>
    </div>

    <div class="control-group form-group">
        <div class="controls form-group has-feedback">
            <label>Telefone*</label>
            <input type="tel" class="form-control" id="phone" required data-validation-required-message="Por favor, insira seu número de telefone." >
            <i class="fa fa-phone form-control-feedback"></i>
        </div>
    </div>

    <div class="control-group form-group">
        <div class="controls form-group has-feedback">
            <label>Email*</label>
            <input type="email" class="form-control" id="email" required data-validation-required-message="Por favor, insira seu email.">
            <i class="fa fa-envelope form-control-feedback"></i>
        </div>
    </div>

    <div class="control-group form-group">
        <div class="controls form-group has-feedback">
            <label>Mensagem</label>
            <textarea rows="10" cols="100" class="form-control" id="message" maxlength="999" style="resize:none" placeholder="Relate sobre sua solicitação ou projeto."></textarea>
        </div>
    </div>

    <div id="success"></div>
    <!-- For success/fail messages -->
    <br>
    <button type="submit" class="btn btn-success btn-lg">Enviar solicitação</button>

</form>

JS:

    /*
  Jquery Validation using jqBootstrapValidation
   example is taken from jqBootstrapValidation docs 
  */
$(function() {

    $("input,textarea").jqBootstrapValidation({
        preventSubmit: true,
        submitError: function($form, event, errors) {
            // something to have when submit produces an error ?
            // Not decided if I need it yet
        },
        submitSuccess: function($form, event) {
            event.preventDefault(); // prevent default submit behaviour
            // get values from FORM
            var name = $("input#name").val();
            var empresa = $("input#empresa").val();
            var phone = $("input#phone").val();
            var email = $("input#email").val();
            var message = $("textarea#message").val();
            var firstName = name; // For Success/Failure Message
            // Check for white space in name for Success/Fail message
            if (firstName.indexOf(' ') >= 0) {
                firstName = name.split(' ').slice(0, -1).join(' ');
            }
            $.ajax({
                url: "bin/contact_me.php",
                type: "POST",
                data: {
                    name: name,
                    empresa: empresa,
                    phone: phone,
                    email: email,
                    message: message
                },
                cache: false,
                success: function() {
                    // Success message
                    $('#success').html("<div class='alert alert-success'>");
                    $('#success > .alert-success').html("<button type='button' class='close' data-dismiss='alert' aria-hidden='true'>&times;")
                        .append("</button>");
                    $('#success > .alert-success')
                        .append("<strong>Sua mensagem foi enviada. </strong>");
                    $('#success > .alert-success')
                        .append('</div>');

                    //clear all fields
                    $('#contactForm').trigger("reset");
                },
                error: function() {
                    // Fail message
                    $('#success').html("<div class='alert alert-danger'>");
                    $('#success > .alert-danger').html("<button type='button' class='close' data-dismiss='alert' aria-hidden='true'>&times;")
                        .append("</button>");
                    $('#success > .alert-danger').append("<strong>" + firstName + " Parece que não está funcionando...</strong> Você poderia enviar um email direto para nós? Desculpe pela inconveniência.");
                    $('#success > .alert-danger').append('</div>');
                    //clear all fields
                    $('#contactForm').trigger("reset");
                },
            })
        },
        filter: function() {
            return $(this).is(":visible");
        },
    });

    $("a[data-toggle=\"tab\"]").click(function(e) {
        e.preventDefault();
        $(this).tab("show");
    });
});


/*When clicking on Full hide fail/success boxes */
$('#name').focus(function() {
    $('#success').html('');
});

PHP:

    <?php

if(empty($_POST['email'])       ||
   !filter_var($_POST['email'],FILTER_VALIDATE_EMAIL))
   {
    echo "No arguments Provided!";
    return false;
   }
$name = $_POST['name'];
$phone = $_POST['phone'];
$empresa = $_POST['empresa'];
$email_address = $_POST['email'];
$message = $_POST['message'];

// create email body and send it    
$to = '[email protected]'; // PUT YOUR EMAIL ADDRESS HERE
$email_subject = "Solicitação de $name, $empresa."; // EDIT THE EMAIL SUBJECT LINE HERE
$email_body = "Uma solicitação foi enviada no site.\n\n"."Aqui estão os detalhes:\n\nNome: $name\n\nTelefone: $phone\n\nEmail: $email_address\n\nMensagem:\n$message";
$headers = "From: $email_address\n";
$headers .= "Reply-To: $email_address"; 
mail($to,$email_subject,$email_body,$headers);
return true;            
?>