后台获取正确格式数据后，zTree 初始化异常?报错

@zTree 你好，想跟你请教个问题：

/**
 * 初始化菜单数
 */ 
 function getMenuTree(){
$('#treeDemo').empty();//清空处理
var setting = {
check: {
enable: true
},
data: {
simpleData: {
enable: true,
idKey:  "menuId",
pIdKey: "menuParentid",
rootPId: 0
},
key: {
name: "parentName"
}
}

};


$.getJSON("/JK_AirPortPro/menu/menu/menuTree.ajax", 
function (data) {
var zNodes = JSON.stringify(data.list);
console.log(zNodes);//输出到控制台
    $.fn.zTree.init($("#treeDemo"), setting, zNodes);//这里前台报错
    setCheck();
$("#py").bind("change", setCheck);
$("#sy").bind("change", setCheck);
$("#pn").bind("change", setCheck);
$("#sn").bind("change", setCheck);
});
}

错误内容如下：

以下这种方式就没有错误

var zNodes =[{"menuId":1,"menuParentid":0,"open":"false","parentName":"远程监控"},
            {"menuId":2,"menuParentid":1,"open":"false","parentName":"工艺监控"},
            {"menuId":3,"menuParentid":2,"open":"false","parentName":"预处理2"},
            {"menuId":4,"menuParentid":2,"open":"false","parentName":"缓冲池"},
            {"menuId":5,"menuParentid":2,"open":"false","parentName":"曝气池"},
            {"menuId":6,"menuParentid":0,"open":"false","parentName":"首页"},
            {"menuId":7,"menuParentid":2,"open":"false","parentName":"厌氧池"}] ;
       
$.fn.zTree.init($("#treeDemo"), setting, zNodes);
setCheck();
$("#py").bind("change", setCheck);
$("#sy").bind("change", setCheck);
$("#pn").bind("change", setCheck);
$("#sn").bind("change", setCheck);