关于ajax json返回值的问题

function aa (){
debugger;
var cardID = IAEnthreeDes("74f9b968,2704122125150801");
var option = IAEnthreeDes("74f9b968,admin");
var price = IAEnthreeDes("74f9b968,110");
var url = "192.168.1.32:8080/Interface/GeneralInterfaceHandler.ashx";
var postStr = "do=GetDiscountMoney&CompCode=''&ShopID=''&CardIDorMobile=" + cardID + "& TotalMoney=" + price + "&MasterAccount=" + option + "&WeChatID=''";
$.ajax({
url: url,
data: postStr,
type:'post',
dataType:'json',
success:function(data) {
//callback(data);
alert(data);
},
error: function (xhr, type, exception) {//获取ajax的错误信息
alert(xhr.responseText, "Failed");
}
});
}
返回值弹窗：undefined 请问我这是哪里出错了