[jQuery] simple code not working

[kikloo]

hi

i have this simple code:

$(function() {
        $("select#ctlByName").change(function() {

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

and its not working. Its set to work when a <select> is changed by
user and it should then get data back from ajax.php which is sending
the data fine. But no alert is coming up and it seems its not working.

Please help.

Thanks.