JavaFX绑定layoutY :无法设置绑定值

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

public class Main extends Application {

    @Override
    public void start(Stage primaryStage) {
        Button button1 = new Button("Button 1");
        Button button2 = new Button("Button 2");

        // 将button2的layoutY属性绑定到button1的layoutY属性上
        button2.layoutYProperty().bind(button1.layoutYProperty());

        VBox vbox = new VBox(button1, button2);
        Scene scene = new Scene(vbox, 200, 200);

        primaryStage.setScene(scene);
        primaryStage.show();
    }

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