Jquery Ajax hitting error function

I have a Jquery ajax code which works on some website and same code don't work when i use on other website.

<script type="text/javascript">
    function check_domain( d, e){
        $.ajax({
                type: "POST",
                url: "ajax.php?domain=" + d,
                success: function(data){
                    var ele = $("." + e);
                    ele.find("td.td_emails").html(data);

                },
                error: function() {
                    alert('Error occurs!');
                }
        });
    }
</script>

i am calling this function in html like this

<script type="text/javascript">check_domain("http%3A%2F%2Fwww.1smile.co.uk%2F", "tr_12");</script>

But it go to ajax error function rather going to success function on some domains and on other it works fine. Please point out the error.