Create a pannable map background in JavaFX

PannableView.java

import javafx.application.Application;
import static javafx.application.Application.launch;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.ScrollPane;
import javafx.scene.image.Image;
import javafx.scene.image.ImageView;
import javafx.scene.layout.Pane;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;

/** Constructs a scene with a pannable Map background. */
public class PannableView extends Application {
  private Image backgroundImage;
  
  @Override public void init() {
    backgroundImage = new Image("http://www.narniaweb.com/wp-content/uploads/2009/08/NarniaMap.jpg");
  }
  
  @Override public void start(Stage stage) {
    stage.setTitle("Drag the mouse to pan the map");
    
    // construct the scene contents over a stacked background.
    StackPane layout = new StackPane();
    layout.getChildren().setAll(
      new ImageView(backgroundImage),
      createKillButton()
    );

    // wrap the scene contents in a pannable scroll pane.
    ScrollPane scroll = createScrollPane(layout);
    
    // show the scene.
    Scene scene = new Scene(scroll);
    stage.setScene(scene);
    stage.show();

    // bind the preferred size of the scroll area to the size of the scene.
    scroll.prefWidthProperty().bind(scene.widthProperty());
    scroll.prefHeightProperty().bind(scene.widthProperty());
    
    // center the scroll contents.
    scroll.setHvalue(scroll.getHmin() + (scroll.getHmax() - scroll.getHmin()) / 2);
    scroll.setVvalue(scroll.getVmin() + (scroll.getVmax() - scroll.getVmin()) / 2);
  }
  
  /** @return a control to place on the scene. */
  private Button createKillButton() {
    final Button killButton = new Button("Kill the evil witch");
    killButton.setStyle("-fx-base: firebrick;");
    killButton.setTranslateX(65);
    killButton.setTranslateY(-130);
    killButton.setOnAction(new EventHandler<ActionEvent>() {
      @Override public void handle(ActionEvent t) {
        killButton.setStyle("-fx-base: forestgreen;");
        killButton.setText("Ding-Dong! The Witch is Dead");
      }
    });
    return killButton;
  }

  /** @return a ScrollPane which scrolls the layout. */
  private ScrollPane createScrollPane(Pane layout) {
    ScrollPane scroll = new ScrollPane();
    scroll.setHbarPolicy(ScrollPane.ScrollBarPolicy.NEVER);
    scroll.setVbarPolicy(ScrollPane.ScrollBarPolicy.NEVER);
    scroll.setPannable(true);
    scroll.setPrefSize(800, 600);
    scroll.setContent(layout);
    return scroll;
  }
  
  public static void main(String[] args) { launch(args); }  
}

thanks, I learned a lot from this!

This Code only produces an empty scene for me.
The ScrollPane seems to be present, but the image and button aren't.
Can you check on that?
I use JavaFX8 3.7.0, apparently.

Update: Changing the URL to use https instead of http fixes it ^^