Simple http server doesn't work

i hava an account on openshift with a cartridge of node.js

this is my server.js

var http = require('http');

var server = http.createServer(function(req, res) {
    res.writeHead(200);
    res.end('Hello Http');
});
server.listen(process.env.OPENSHIFT_NODEJS_PORT || 3000);;

this is the package.json file

{
  "name": "OpenShift-Sample-App",
  "version": "1.0.0",
  "description": "OpenShift Sample Application",
  "keywords": [
    "OpenShift",
    "Node.js",
    "application",
    "openshift"
  ],
  "author": {
    "name": "OpenShift",
    "email": "ramr@example.org",
    "url": "http://www.openshift.com/"
  },
  "homepage": "http://www.openshift.com/",
  "repository": {
    "type": "git",
    "url": "https://github.com/openshift/origin-server"
  },

  "engines": {
    "node": ">= 0.6.0",
    "npm": ">= 1.0.0"
  },

  "dependencies": {
    "express": "~3.4.4"
  },
  "devDependencies": {},
  "bundleDependencies": [],

  "private": true,
  "main": "server.js"
}

and the app works on localhost with node server.js. what is the problem?

log

events.js:72
        throw er; // Unhandled 'error' event
              ^
Error: listen EACCES
    at errnoException (net.js:901:11)
    at Server._listen2 (net.js:1020:19)
    at listen (net.js:1061:10)
    at Server.listen (net.js:1135:5)
    at Object.<anonymous> (/var/lib/openshift/5423abc786asbcbasd89c/app-root/runtime/repo/server.js:7:8)
    at Module._compile (module.js:456:26)
    at Object.Module._extensions..js (module.js:474:10)
    at Module.load (module.js:356:32)
    at Function.Module._load (module.js:312:12)
    at Function.Module.runMain (module.js:497:10)
DEBUG: Program node server.js exited with code 8
DEBUG: Starting child process with 'node server.js'