Mongodb not showing my Aggregation - node.js

Question

I am currently having trouble with showing my aggregation records. I wanted to show the summed up value for all the documents but its not showing. It keeps showing me the Records not found only. I don't know where i have gone wrong. Someone help me out.
var express = require('express');
var app = express();
var mongojs = require('mongojs');
var db = mongojs('meibanlist', ['contact']);
var bodyParser = require('body-parser');
app.use(express.static(__dirname + '/public'));
app.use(bodyParser.json());
app.get('/meibanlist', function (req, res) {
console.log('I received a GET request');
db.meibanlist.find(function (err, docs) {
console.log(docs);
res.json(docs);
});
});
app.post('/meibanlist', function (req, res) {
console.log(req.body);
db.meibanlist.insert(req.body, function(err, doc) {
res.json(doc);
});
});
app.delete('/meibanlist/', function (req, res) {
console.log();
db.meibanlist.remove(function (err, doc) {
res.json(doc);
});
});
app.get('/meibanlist/', function (req, res) {
console.log();
db.meibanlist.findOne(function (err, doc) {
res.json(doc);
});
});
app.put('/meibanlist/', function (req, res) {
console.log(req.body.machine_Id);
db.meibanlist.findAndModify({
query: {_id: mongojs.machine_Id},
update: {$set: {machine_Id: req.body.machine_Id, air_Temp: req.body.air_Temp, water_Temp: req.body.water_Temp, heat_Temp: req.body.heat_Temp, room_Temp: req.body.room_Temp, date:req.body.date, time: req.body.time}},
new: true}, function (err, doc) {
res.json(doc);
}
);
});
db.contact.aggregate([{$group: {machine_Id : "$machine_Id", air_Temp : {$sum : "$likes"}}}], function(err, meibanlist) {
if( err || !meibanlist ) console.log("Record not found");
else meibanlist.forEach (function(machine_Id){
console.log(machine_Id);
});
});
app.listen(3000);
console.log("Server running on port 3000");