undefine variable in ajax

undefine variable in ajax

i am posting hCenter div's html in result.php page. i tried it val() also but error is head not defined.
function headerT() {
        valhead = "";
            valhead = $("#hCenter").html();
            alert(valhead);
        $.ajax( {
            url: 'result.php',
            type: 'post',
            data: "head="+valhead
        })
        .done ( function (msg) {
        });
    }
result.php
echo $_POST['head'];
please help me