JPanel setBackground(Color.BLACK) does nothing

I have the folowing custom JPanel and I have aded it to my frame using Netbeans GUI builder but the background won't change! I can see the circle, drawing with g.fillOval(). What's wrong? ``` public class Board extends JPanel{ private Player player; public Board(){ setOpaque(false); setBackground(Color.BLACK); } public void paintComponent(Graphics g){ super.paintComponent(g); g.setColor(Color.red); g.fillOval(player.getxCenter(), player.getyCenter(), player.getRadius(), player.getRadius()); } public void updatePlayer(Player player){ this.player=player; } } ```