git push heroku master Building dependencies error - heroku

Question

i am using heroku and my server is written in Node JS.
while trying
git push heroku master
I am am getting the following Error
remote: Building source:
remote:
remote: -----> Node.js app detected
remote:
remote: -----> Creating runtime environment
remote:
remote: NPM_CONFIG_LOGLEVEL=error
remote: NPM_CONFIG_PRODUCTION=true
remote: NODE_ENV=production
remote: NODE_MODULES_CACHE=true
remote:
remote: -----> Installing binaries
remote: engines.node (package.json): 4.1.2
remote: engines.npm (package.json): unspecified (use default)
remote:
remote: Downloading and installing node 4.1.2...
remote: Using default npm version: 2.14.4
remote:
remote: -----> Restoring cache
remote: Skipping cache restore (new runtime signature)
remote:
remote: -----> Building dependencies
remote: Pruning any extraneous modules
remote: Installing node modules (package.json)
remote: npm ERR! Linux 3.13.0-85-generic
remote: npm ERR! argv "/tmp/build_a220092b4f1662f47548204bbda7d972/.heroku/node/bin/node" "/tmp/build_a220092b4f1662f47548204bbda7d972/.heroku/
node/bin/npm" "install" "--unsafe-perm" "--userconfig" "/tmp/build_a220092b4f1662f47548204bbda7d972/.npmrc"
remote: npm ERR! node v4.1.2
remote: npm ERR! npm v2.14.4
remote:
remote: npm ERR! version not found: e#2.7.1
remote: npm ERR!
remote: npm ERR! If you need help, you may report this error at:
remote: npm ERR! <https://github.com/npm/npm/issues>
remote:
remote: npm ERR! Please include the following file with any support request:
remote: npm ERR! /tmp/build_a220092b4f1662f47548204bbda7d972/npm-debug.log
my package.json file looks like this
{
"name": "myServerTry",
"version": "1.0.0",
"description": "InfoBroker application",
"engines": {
"node": "4.1.2"
},
"main": "server.js",
"scripts": {
"test": "echo \"Error: no test specified\" && exit 1",
"start": "node server.js"
},
"dependencies": {
"body-parser": "^1.14.1",
"connect": "^3.4.0",
"cors": "^2.7.1",
"express": "^4.13.3",
"express-csv": "^0.6.0",
"foobar": "^1.1.0",
"e": "^0.0.4",
"mysql": "^2.9.0",
"q": "^1.4.1",
"qs": "^6.0.0",
"underscore": "^1.8.3"
},
"keywords": [],
"author": "",
"license": "ISC"
}
In my local files, everything is working just fine.
I also checked the version of the dependencies and it is all right.
any ideas?