image problem

/**
 * Sample React Native App
 * https://github.com/facebook/react-native
 * This is for test image bugs constant
 * @flow
 */

import React, { Component } from 'react';
import {
  Platform,
  StyleSheet,
  Text,
  View,
  Image
} from 'react-native';


export default class App extends Component<{}> {
  constructor(props){
    super(props);
    this.state= {
      url:"https://en.facebookbrand.com/wp-content/uploads/2016/05/FB-fLogo-Blue-broadcast-2.png" 
    }
  }
  render() {
    let link_test ="https://en.facebookbrand.com/wp-content/uploads/2016/05/FB-fLogo-Blue-broadcast-2.png";
    return (
      <View style={styles.container}>
        <Text style={styles.welcome}>
          Normal image link
        </Text>
        <Image source= {{ uri:"https://en.facebookbrand.com/wp-content/uploads/2016/05/FB-fLogo-Blue-broadcast-2.png" }}  style={{ width:100,height:100 }}/>
        <Text>Image link using standard variable</Text>
        <Image source ={{ uri:link_test }} />
        <Text>Image  using state </Text>
        <Image source ={{ uri:this.state.url }} />
        <Text>{this.state.url}</Text>
      </View>
    );
  }
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',
    alignItems: 'center',
    backgroundColor: '#F5FCFF',
  },
  welcome: {
    fontSize: 20,
    textAlign: 'center',
    margin: 10,
  },
  instructions: {
    textAlign: 'center',
    color: '#333333',
    marginBottom: 5,
  },
});