wx.getSetting({})调用失败是什么原因？

    wx.getSetting({

      withSubscriptions: true,

      success(res) {

        var itemSettings = res.subscriptionsSetting.itemSettings;

        if (itemSettings) {

          if (itemSettings['']=='accept') {

            console.log('========已经授权订阅消息=====')

            // _this.selectComponent("#authorizeMsg").show();

          }else{

            console.log("========未授权订阅消息=====");

            _this.selectComponent("#authorizeMsg").show();

          }

        }

      },fail(res){

        console.log("getSettingERROR:",res);

      }

    })