Jquery数据表不发出数据检索

我使用jQuery DataTable通过c# web方法来填充表格的AJAX请求。我的问题是没有返回任何数据或任何错误。有人能帮我吗?

var TableAjax = function () {
    var initPickers = function () {
        //init date pickers
        $('.date-picker').datepicker({
            rtl: Metronic.isRTL(),
            autoclose: true
        });
     }
    var handleRecords = function () {
    var grid = new Datatable();
    grid.init({
        src: $("#datatable_ajax"),
        onSuccess: function (grid) {
            // execute some code after table records loaded
        },
        onError: function (grid) {
            // execute some code on network or other general error  
        },
        onDataLoad: function (grid) {
            // execute some code on ajax data load
        },
        loadingMessage: 'Loading...',
        DataTable: { // here you can define a typical datatable settings from http://datatables.net/usage/options 
            // Uncomment below line("dom" parameter) to fix the dropdown overflow issue in the datatable cells. The default datatable layout
            // setup uses scrollable div(table-scrollable) with overflow:auto to enable vertical scroll(see: assets/global/scripts/datatable.js). 
            // So when dropdowns used the scrollable div should be removed. 
            //"dom": "<'row'<'col-md-8 col-sm-12'pli><'col-md-4 col-sm-12'<'table-group-actions pull-right'>>r>t<'row'<'col-md-8 col-sm-12'pli><'col-md-4 col-sm-12'>>",
            "bStateSave": true, // save datatable state(pagination, sort, etc) in cookie.
            "lengthMenu": [
                [10, 20, 50, 100, 150, -1],
                [10, 20, 50, 100, 150, "All"] // change per page values here
            ],
            "pageLength": 10, // default record count per page
            "ajax": {
                url: "/WS/WS.asmx/GetCustomers",
                type: 'GET',
                dataType: 'json',
                contentType: 'application/json; charset=utf-8',
            },
            "aoColumns": [
              { "mData": "CustomerAddress" },
              { "mData": "CustomerName" },
              { "mData": "CustomerCode" },
              { "mData": "CustomerCode" },
              { "mData": "CustomerCode" },
              { "mData": "CustomerCode" },
              { "mData": "CustomerCode" }
            ],
            "order": [
                [1, "asc"]
            ]// set first column as a default sort by asc
        }
    });
    // handle group actionsubmit button click
    grid.getTableWrapper().on('click', '.table-group-action-submit', function (e) {
        e.preventDefault();
        var action = $(".table-group-action-input", grid.getTableWrapper());
        if (action.val() != "" && grid.getSelectedRowsCount() > 0) {
            grid.setAjaxParam("CustomerId", "group_action");
            grid.setAjaxParam("CustomerName", action.val());
            grid.setAjaxParam("id", grid.getSelectedRows());
            grid.getDataTable().ajax.reload();
            grid.clearAjaxParams();
        } else if (action.val() == "") {
            Metronic.alert({
                type: 'danger',
                icon: 'warning',
                message: 'Please select an action',
                container: grid.getTableWrapper(),
                place: 'prepend'
            });
        } else if (grid.getSelectedRowsCount() === 0) {
            Metronic.alert({
                type: 'danger',
                icon: 'warning',
                message: 'No record selected',
                container: grid.getTableWrapper(),
                place: 'prepend'
            });
        }
    });
}
return {
    //main function to initiate the module
    init: function () {
        initPickers();
        handleRecords();
    }
};
}();

和我的web方法代码:

[WebMethod(EnableSession = true)]
[ScriptMethod(UseHttpGet = true, ResponseFormat = ResponseFormat.Json)]
public object GetCustomers()
{
    DataTable dt = ICMS_DB_CLS.GetDataFromDB("Select * from  t_crm_customers");
    List<Customers> lis = new List<Customers>();
    lis = ExtensionList.ToListof<Customers>(dt);
    return new
    {
        data = lis,
        length = lis.Count
    };
}

我的问题不返回任何数据或任何错误。