[Node js application not working]

So, i'm trying to setup a nodejs app using the "setup a nodejs app" option in cpanel. But when I try to access the URL where the app is running I get a 503 service unavailable. I have attached a pic of the information used to setup the app. Also, the contents of the application startup file which is index.js is 

 

var http = require('http');
var server = http.createServer(function(req, res) {
    res.writeHead(200, {'Content-Type': 'text/plain'});
    var message = 'It works!\n',
        version = 'NodeJS ' + process.versions.node + '\n',
        response = [message, version].join('\n');
    res.end(response);
});
server.listen();

 

This is basically the default text which hawk host adds to the startup file. This code as it is gave me a 503 service unavailable error , so I tried adding a port number to the server.listen() but I still get the same error.