jQuery.ajax中获取不到返回值，返回值是从数据库中查询出来的解决办法

function SaveClick() {    var Price1 = 0;    for (var i = 1; i <= 10; i++) {        var SumPrice = $("#txtSumPrice" + i).val();        if (SumPrice != "") {            Price1 = Price1 + parseFloat(SumPrice);        }    }    var SupplierId1 = parseInt($("#ddSupplierList").val());    var Performance1 = "1";    var Time2 = $("#Calendar").val().replace(/-/g, "/");    $.ajax({ //利用Ajax调用Web服务中的数据，实现与后台交互        type: "POST",        contentType: "application/json;utf-8",        url: "WebService.asmx/addPurchaseOrders",        data: "{ 'SupplierId' :'" + SupplierId1 + "', 'Price' :'" + Price1 + "', 'Performance' :'" + Performance1.toString() + "', 'Time1':'" + Time2 + "'}",        //data: "{ 'SupplierId' :" + SupplierId1 + ", 'Price' :" + Price1 + ", 'Performance' :" + Performance1.toString() + ", Time1:'" + Time2 + "'}",        //data: "{ 'SupplierId' :" + SupplierId1 + ", 'Price' :" + Price1 + ", 'Performance' :" + Performance1 + "}",        dataType: 'json',        anysc: false,        success: function (data) {            alert("ok");           // alert(data.d);            //SaveClickContent(data.d);        },        error: function (XMLResponse) {            alert(XMLResponse.responseText);            alert("false");        }    })}

[WebMethod]    public string addPurchaseOrders(int SupplierId, decimal Price, string Performance, string Time1  )    {              string str="";       BLL.PurchaseOrder bll = new BLL.PurchaseOrder();       Model.PurchaseOrder model = new Model.PurchaseOrder();       model.SupplierId = SupplierId;       model.Price = Price;       if (Performance == "1")       {           model.Performance = "保存";       }       model.RecTime = DateTime.Parse(Time1);       if (bll.Add(model))       {           str = bll.SearchLastId().ToString();           return str;       }              return str;    }