Realm is getting error : Error: Cannot find module 'realm' .

I am creating an app where I using Realm, and all of sudden I am getting this error when doing node index.js which I get Error: Cannot find module 'realm'

and when I do npm install I get this error: Could not install /**********/realm-professional.tgz

Here are the code.

    'use strict';

var fs = require('fs');
var Realm = require('realm');
var VisualRecognition = require('watson-developer-cloud/visual-recognition/v3');


var REALM_ADMIN_TOKEN = "***************";



var BLUEMIX_API_KEY = "***********";


var SERVER_URL = 'realm://127.0.0.1';


var NOTIFIER_PATH = ".*/*****"; 

The Json file

    {
  "name": "MyApp",
  "version": "0.0.1",
  "description": "Use Realm Object Server's event-handling.",
  "main": "index.js",
  "author": "Realm",
  "dependencies": {
    "realm": "file:realm-professional.tgz",
    "watson-developer-cloud": "^2.11.0"
  }
}

via Jośe