Get data Client Side using Ajax call

Hi,

I'm struggling to load data from a ajax cal into a asp.net c# web method. My code is:

var oMessageDate;
var tblData;
$(document).ready(function () {

getData();

oMessageDate = $("#tblDataTable").DataTable({
    data: tblData
});

});

function getData() {
$.ajax({
type: "POST",
url: "DataTable.aspx/GetSummary",
data: "{}",
dataType: "json",
contentType: "application/json; charset=utf-8",
success: function (result) {
tblData = result.d;
}
});
}

my DataTable is empty, but I get the results from the web method.

What am i doing wrong?