JavaFx Button Event Handler to move shapes

I just started JavaFx this past week and having a problem trying to get a circle setup in a pane to respond to button event handler. I have buttons setup with names left, right, up, down which when pressed should move the circle inside inside the pane. My problem is I can't get the circle to respond to my event handlers at all. I saw another tutorial that incorporated key presses to move the circle and I'm trying something similar but with buttons instead. Any help in getting me in the right direction would be great thanks.

package movingball;

import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.HBox;
import javafx.scene.layout.StackPane;
import javafx.scene.paint.Color;
import javafx.scene.shape.Circle;
import javafx.stage.Stage;

public class MovingBall extends Application{
  private CirclePane circlePane = new CirclePane();


@Override
public void start(Stage primaryStage) {
    StackPane pane = new StackPane();
    Circle circle = new Circle(50);
    circle.setStroke(Color.BLACK);
    circle.setFill(Color.WHITE);
    pane.getChildren().add(circle);

    HBox hBox = new HBox();
    hBox.setSpacing(10);
    hBox.setAlignment(Pos.CENTER);
    Button btLeft = new Button("Left");
    Button btRight = new Button("Right");
    Button btUp = new Button("Up");
    Button btDown = new Button("Down");
    hBox.getChildren().addAll(btLeft, btRight, btUp, btDown);

    btLeft.setOnAction(new LeftHandler());
    btRight.setOnAction(new RightHandler());
    btUp.setOnAction(new UpHandler());
    btDown.setOnAction(new DownHandler());


    BorderPane borderPane = new BorderPane();
    borderPane.setCenter(pane);
    borderPane.setBottom(hBox);
    BorderPane.setAlignment(hBox, Pos.CENTER);

    // Create a scene and place it in the stage
    Scene scene = new Scene(borderPane, 500, 350);
    primaryStage.setTitle("Move the Ball"); // Set the stage title
    primaryStage.setScene(scene); // Place the scene in the stage
    primaryStage.show(); // Display the stage
  }



class LeftHandler implements EventHandler<ActionEvent> {

    @Override
    public void handle(ActionEvent event) {
        circlePane.left();

    }

}

class RightHandler implements EventHandler<ActionEvent> {

    @Override
    public void handle(ActionEvent event) {
        circlePane.right();

    }

}

class UpHandler implements EventHandler<ActionEvent> {

    @Override
    public void handle(ActionEvent event) {
        circlePane.up();

    }

}

class DownHandler implements EventHandler<ActionEvent> {

    @Override
    public void handle(ActionEvent event) {
        circlePane.down();

    }

}

class CirclePane extends StackPane {
    private Circle circle = new Circle(50);

    public CirclePane() {
        getChildren().add(circle);
        circle.setStroke(Color.BLACK);
        circle.setFill(Color.WHITE);
    }

    public void left() {
        circle.setCenterX(circle.getCenterX() - 10);
    }

    public void right() {
        circle.setCenterX(circle.getCenterX() + 10);
    }

    public void up() {
        circle.setCenterY(circle.getCenterY() - 10);
    }

    public void down() {
        circle.setCenterY(circle.getCenterY() + 10);
    }
}


  public static void main(String[] args) {
    launch(args);
  }

}