新手卡住了，请各位帮忙分析下。

问题：编译可以通过，运行程序时键盘不能控制方向？
import java.awt.*;
import java.awt.event.*;public class TankClient extends Frame {
public static final int GAME_WIDHT = 800;
public static final int GAME_HEIGHT = 600;

int x = 50;
int y = 50;
Image offScreenImage = null;

public void paint(Graphics g) {
Color c = g.getColor();
g.setColor(Color.RED);
g.fillOval(x, y, 30, 30);
g.setColor(c);
}

public void update(Graphics g) {
if(offScreenImage == null) {
offScreenImage = this.createImage(GAME_WIDHT, GAME_HEIGHT);
}
Graphics goffScreen = offScreenImage.getGraphics();
Color c = goffScreen.getColor();
goffScreen.setColor(Color.GREEN);
goffScreen.fillRect(0, 0, GAME_WIDHT, GAME_HEIGHT);
goffScreen.setColor(c);
paint(goffScreen);
g.drawImage(offScreenImage, 0, 0, null);
}

public void lauchFrame() {
this.setLocation(400, 300);
this.setSize(GAME_WIDHT, GAME_HEIGHT);
this.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
this.setTitle("TankWar");
this.setResizable(false);
this.setBackground(Color.GREEN);
this.addKeyListener(new KeyMonitor());
setVisible(true);
new Thread(new PaintThread()).start();

}

public static void main(String[] args) {
TankClient tc = new TankClient();
tc.lauchFrame();
}

private class PaintThread implements Runnable {

public void run() {
while(true) {
repaint();
try {
Thread.sleep(50);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}

private class KeyMonitor extends KeyAdapter {

public void KeyPressed(KeyEvent e) {
int Key = e.getKeyCode();
switch(Key) {
case KeyEvent.VK_LEFT:
x -= 5;
break; 
case KeyEvent.VK_UP:
y -= 5;
break; 
case KeyEvent.VK_RIGHT:
x += 5;
break; 
case KeyEvent.VK_DOWN:
y += 5;
break; 
}
}
}

}