Node.js: Simple app not working on Heroku

I've written a basic node.js application and I've managed to deploy it on Heroku without having any problem. I've created my package.json and Procfile, however from logs I see that there is no running processes, thus cannot get any response. What could be the problem?

PS: I do not want to use the Express framework

My Code:

var http = require("http");

http.createServer(function(request, response) {
  response.writeHead(200, {"Content-Type": "text/plain"});
  response.write("Hello World");
  response.end();

  console.log("I am working");
}).listen(8888);

My package.json:

{
  "name": "node-example",
  "version": "0.0.1",
  "dependencies": {
  },
  "engines": {
    "node": "0.8.x",
    "npm": "1.1.x"
  }
}

Logs:

2012-10-22T12:36:58+00:00 heroku[slugc]: Slug compilation started
2012-10-22T12:37:07+00:00 heroku[slugc]: Slug compilation finished
2012-10-22T12:40:55+00:00 heroku[router]: Error H14 (No web processes running) -> GET aqueous-bastion-6914.herokuapp.com/ dyno= queue= wait= service= status=503 bytes=
2012-10-22T12:50:44+00:00 heroku[router]: Error H14 (No web processes running) -> GET aqueous-bastion-6914.herokuapp.com/ dyno= queue= wait= service= status=503 bytes=

Have you scaled the heroku app?

$ heroku ps:scale web=1

This is a required step. The 1 is the number of processes you want spawned for your app.

Change your port

from

.listen(8888)

to

.listen(process.env.PORT || 8888)

What's inside your Procfile? Does it match your app name?

$ ls
app.js Procfile
$ cat Procfile
web: node app$
$