Angular2 : concurrent is not recognized as internal or external command
<p>While running server for angular2 using npm start is giving error that concurrent is not recognized as internal or external command, why is it happens these kind of error</p>

<p>here is package.json:</p>

<pre><code>{
  "name": "contactlistapp",
  "version": "1.0.0",
  "description": "The app",
  "scripts": {
    "test": "echo \"Error: no test specified\" &amp;&amp; exit 1",
    "tsc": "./node_modules/.bin/tsc",
    "tsc:w": "./node_modules/.bin/tsc -w",
    "serve": "./node_modules/.bin/live-server --host=localhost --port=3000 .",
    "start": "concurrent \"npm run tsc:w\" \"npm run serve\" "
  },
  "author": "Sarah",
  "license": "ISC",
  "dependencies": {
    "express": "^4.13.3",
    "angular2": "2.0.0-beta.0",
    "systemjs": "0.19.6",
    "es6-promise": "^3.0.2",
    "es6-shim": "^0.33.3",
    "reflect-metadata": "0.1.2",
    "rxjs": "5.0.0-beta.0",
    "zone.js": "0.5.10"
  },
  "devDependencies": {
    "concurrently": "^1.0.0",
    "lite-server": "^1.3.1",
    "typescript": "^1.7.3"
  }
}
</code></pre>

<p>structure of the project is there is node_module and typings folder there is app.ts file for server(empty only express is imported), and component.ts(and their .js), tsconfig.json</p>