wx.setTabBarBadge不能在wx.onSocketMessage里吗

wx.onSocketMessage(function (res) {console.log(‘收到服务器内容：’ + res.data)wx.setTabBarBadge({index: 2,text: ‘2’,complete: function (a) {console.log(a)}});})

报错：{errMsg: “setTabBarBadge:fail not TabBar page”}