Turn leapster2 off. Press and hold question mark button, then turn on leapster2. Keep holding the question mark button until you get a screen that says "touch calibration" on the right. Once you get this screen, let go of question mark button. Press the "A" button to select touch calibration. A small "+" will appear in one corner -- touch it with the pen. Repeat this for all four corners and then the middle. You have re-calibrated the pen. You can then turn the leapster2 off and then on again to play.

If you have tried this and the pen still doesn't work, change the batteries and repeat steps above.