Mail chimp 1.3 PHP API on ajax call

functions.php

<?php
require get_template_directory() . '/inc/mailchipapi.php';
add_action('wp_ajax_add_to_mailchimp_list', 'add_to_mailchimp_list', 0);
add_action('wp_ajax_nopriv_add_to_mailchimp_list', 'add_to_mailchimp_list');

function add_to_mailchimp_list() {
	
	$apiKey = 'YOUR_API_KEY';
                $listId = 'YOUR_LIST_ID'; // End Customer       
	$double_optin=false;
	$send_welcome=false;
	$email_type = 'html';
	$email = $_POST['email'];

	$api = new MCAPI($apiKey);

	$retval = $api->listSubscribe( $listId, $email,"", "", "false");

	if ($api->errorCode){
		echo $api->errorMessage;
	} else {
	    echo "Thank you for Subscription, you are added to our list!";
	}
	
	die();
}
?>

index.php

<div class="col-sm-6 col-sm-6-2">            	
            	<form class="form-inline" role="form" id="mailchimp" name="subscribe-form" method="POST">
                	<div class="form-group">
                    	<input id="fname" type="text" name="name" placeholder="Name" value="">
                        <input id="email" type="email" name="email" placeholder="Email Address" value="">
                        <span id="ajax-overlay" >
                        	<input type="submit" value="Sign Up +" type="submit" class="btn" id="subscription-submit">
                        	<span class="ajax-loader" style="display:none;"></span>
                         </span>
                    </div>
                    <!-- <div class="subscription-loader"><</div> -->
                </form>
                <p class="notice"></p>
            </div><!--col-sm-6 ends-->
<script>
$('form#mailchimp').submit(function(e) {
		e.preventDefault();

		$('.ajax-loader').show();
        $('#ajax-overlay').addClass('submitted');
		$(this).ajaxSubmit({
            // jQuery('#subscription-submit').attr('disabled');
			success	: function (responseText) {
					$('.ajax-loader').hide();
                    $('#ajax-overlay').removeClass('submitted');
					$('p.notice').text(responseText).fadeIn('slow');

                    if( responseText === 'Thank you for Subscription, you are added to our list!' ) {
                //        
                    }
                    $('#fname').val('');
                    $('#email').val('');
					
			},
			url		: ajaxVars.ajaxurl,
			data	: { ajax_nonce : ajaxVars.ajax_nonce, action : 'add_to_mailchimp_list' },
			type	: 'POST',
			timeout	: 50000,
		});
	});
</script>