getjson not returning data

getjson not returning data

Hello,

I have this basic code following and its not returning anything at all. Even the alert is not alerting. I have checked and the select is sending the value fine But nothing happens on return. What i am missing?

$(function() {
        $("select#ctlByName").change(function() {
       
                cid = $(this).val();
                $.getJSON("ajax.php",{cid:cid}, function(json) {
                        alert("Data Loaded: " + json);
                })
        })
})


Please help.

Thanks.