Node.js app is not working on heroku

I have developed an node.js chat app when i run it in localhost it works fine but not working in heroku

here is my package.json

[{
  "name": "iochat",
  "version": "1.0.0",
  "description": "simple chat app",
  "main": "server.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "Fazal",
  "license": "ISC",
  "dependencies":{
    "socket.io":"2.0.1",
    "express":"4.15.3"
  },
   "engines": {
    "node": "6.10.3"
  }
}]

Not Working Screenshot

Working Screenshot

via Fazal Hussain