Error Deploying node js app to AWS Elastic Beanstalk

I deployed node js application to AWS EBS. When I run the app, i get the error " 502 Bad Gateway " nginx/1.6.2 . This is what i found out in the log.

env.elasticbeanstalk.com/" 2015/04/21 10:52:01 [error] 3807#0: *86 connect() failed (111: Connection refused) while connecting to upstream, client: 172.31.4.86, server: , request: "GET / HTTP/1.1", upstream: "http://127.0.0.1:8081/", host: "clinicaltrials-env.elasticbeanstalk.com"

This is my package.json file

{
"name": "Clinical_Trial_Analytics",
"version": "1.3.2",
"private": true,
"scripts": {
    "start": "node app"
  },
"dependencies": {
    "express": "3.0.6",
    "stylus": "0.31.0",
    "jade": "0.27.7",
    "mongodb": "1.2.7",
    "moment" : "1.7.2",
    "emailjs": "0.3.3",
    "json2html": "1.0.0"
},
"engines": {
    "node": "0.12.0",
    "npm":  "1.1.65"
}
}

I am unable to figure out the issue. Is it with the node version or any other problem? Thanks in advance.