title: Error when trying to use drawer for react native
body: <pre><code>import React, { Component } from "react";
  import {
    StyleSheet,
    Text,
    View
  
  } from "react-native";
  
  //library imports
  import { DrawerNavigator } from 'react-navigation'
  import HomeScreen from './HomeScreen'
  import SettingsScreen from './SettingsScreen'
  
  class App extends Component {
    render() {
      return (
        &lt;MyApp /&gt;
      );
        }
  }
  
  const MyApp = DrawerNavigator({
    Home: {
      screen: HomeScreen
    },
    Settings: {
      screen: SettingsScreen
    }
  })
  export default App;
  styles = StyleSheet.create({
    container: {
      flex: 1,
      alignItems: 'center',
      justifyContent: 'center',
    }
  })
  </code></pre>
  
  <p>The above is my main program. I have two more programs for Home screen and the Settings screen.<br>
  I'm following through this <a href="https://www.youtube.com/watch?v=bJmsmrRtMyw" rel="nofollow noreferrer">video</a>. At 3.09, I try to load the app, but it comes up with an error:</p>
  
  <blockquote>
    <p>Invariant Violation: Module Appregistry is not a registered callable module (callingrunApplication).</p>
  </blockquote>
  
  <p>I just started learning React Native 3 days ago and I would really appreciate you answers.</p>