ajax selalu return 0

Dear kawan2 saya mohon pencerahan disini
saya mencoba membuat plugin yg menggunakan ajax tetapi selalu return 0

berikut adalah kode yg saya pakai

<script type=”text/javascript”>
jQuery(document).ready(function(){
jQuery(“#mailinglist”).submit(function() {
if(jQuery(“#mailinglistemail”).val()==””) {
jQuery(“#mailinglist #message”).text(“Please enter your email address.”);
return false;
} else {
var email = jQuery(‘#mailinglistemail’).val();
if(email.indexOf(“@”) == -1 || email.indexOf(“.”) == -1) {
jQuery(“#mailinglist #message”).text(“Please enter a valid email address.”);
return false;
} else {
console.log(“email :” + email);
var data = {
action: ‘join_mailinglist’,
email: email
};
jQuery(“#mailinglistsubmit”).hide();
jQuery(“.ajaxsave”).show();
jQuery.post(“<?php echo admin_url(‘admin-ajax.php’); ?>”, data,
function(response){
jQuery(“.ajaxsave”).hide();
jQuery(“#mailinglistsubmit”).show();
jQuery(“#mailinglist #message”).html(response);
console.log(response);
alert(response);
});
return false;
}
}

});
});
</script>
<form method=”post” id=”mailinglist” action=””>
<div id=”message”></div>
<input type=”text” name=”mailinglistemail” id=”mailinglistemail” />
<input type=”submit” name=”submit” id=”mailinglistsubmit” value=”Join” /><img src=”<?php admin_url(); ?>/wp-admin/images/wpspin_light.gif” alt=”” class=”ajaxsave” style=”display: none;” />
</form>

dan satu file lagi di file admin :
add_action(‘wp_ajax_join_mailinglist’, ‘join_mailinglist_callback’);
add_action(‘wp_ajax_nopriv_join_mailinglist’, ‘join_mailinglist_callback’);

function join_mailinglist_callback() {
global $wpdb;
$email = $_POST[‘email’];
echo $email;

die();
}

mohon koreksi code saya + pencerahannya
any comment would be appreciated

Thanks