Javafx Pendulum Animation - why can't i see my Circle on scene?

Java program. Using latest version of eclipse and java. Program works just as it should but I cant figure out why I cannot see the circle at the bottom of the pendulum. The program should show the pendulum as a line connecting a top and bottom circle. I've tried moving around the setFill() and setStroke() code and still can't figure this one out...probably something small and simple but I'm missing it. Let me know whats right in front of me please!

import javafx.animation.PathTransition;
import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.Pane;
import javafx.scene.layout.VBox;
import javafx.scene.paint.Color;
import javafx.scene.shape.Arc;
import javafx.scene.shape.Circle;
import javafx.scene.shape.Line;
import javafx.stage.Stage;
import javafx.util.Duration;

public class Ch15PA2 extends Application {
    
    public void start(Stage primaryStage) {
        
        BorderPane pane = new BorderPane();
        VBox vbox = new VBox();
        pane.getChildren().add(vbox);
        
        Pendulum pendulum = new Pendulum(500, 300);
        pane.setCenter(pendulum);   
        
        Scene scene = new Scene(pane,500,500);
        primaryStage.setTitle("Chapter 15 Programming Assignemnt 2");
        primaryStage.setScene(scene);
        pendulum.resume();
        primaryStage.show();
        
        scene.setOnKeyPressed(e -> {
            switch (e.getCode()) {
            case UP: pendulum.increase(); break;
            case DOWN: pendulum.decrease(); break;
            case R: pendulum.resume(); break;
            case S: pendulum.stop(); break;
            }
        });
    }

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

}

class Pendulum extends Pane {
    private double w=300;
    private double h;
    
    PathTransition pt;
    Circle topCircle = new Circle();
    Circle bottomCircle = new Circle();
    Line line;
    Arc arc;
    
    public Pendulum(double width,double height) {
        w = width;
        h = height;
        
        arc = new Arc(w/2,h*.8,w*.15,w*.15,180,180);
        topCircle = new Circle(arc.getCenterX()-arc.getRadiusX(),arc.getCenterY(),10);
        bottomCircle = new Circle(arc.getCenterX(),arc.getCenterY()-h/2,bottomCircle.getRadius()/2);
        arc = new Arc(topCircle.getCenterX(),topCircle.getCenterY(),w/2,h/2,240,60);
        arc.setFill(Color.TRANSPARENT);
        line = new Line(topCircle.getCenterX(),topCircle.getCenterY(),bottomCircle.getCenterX(),bottomCircle.getCenterY());
        pt = new PathTransition();
        pt.setDuration(Duration.seconds(2.0));
        pt.setPath(arc);
        pt.setNode(bottomCircle);
        pt.setOrientation(PathTransition.OrientationType.NONE);
        pt.setCycleCount(PathTransition.INDEFINITE);
        pt.setAutoReverse(true);
        topCircle.setStroke(Color.BLACK);
        topCircle.setFill(Color.BLACK);
        bottomCircle.setStroke(Color.BLACK);
        bottomCircle.setFill(Color.BLACK);
        line.setStroke(Color.BLACK);
        line.endXProperty().bind(bottomCircle.translateXProperty().add(bottomCircle.getCenterX()));
        line.endYProperty().bind(bottomCircle.translateYProperty().add(bottomCircle.getCenterY()));

        getChildren().add(line);
        getChildren().add(bottomCircle);
        getChildren().add(topCircle);
        getChildren().add(arc);
        
    }
    
    public void increase() {
        pt.setRate(pt.getRate()+1);
    }
    
    public void decrease() {
        pt.setRate(pt.getRate()-1);
    }
    
    public void resume() {
        pt.play();
    }
    
    public void stop() {
        pt.stop();
    }
}