For last video tutorial "Adding Sounds" I receive Error for playSound(); under Main Activity

            // Update the label with our dynamic answer
            mAnswerLabel.setText(answer);

            animateCrystalBall();
            animateAnswer();
error here  >>> playSound();

        }
    });
}

private CrystalBall mCrystalBall = new CrystalBall();
private TextView mAnswerLabel;
private Button mGetAnswerButton;
private ImageView mCrystalBallImage;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    // Assign the the Views from the layout file
    mAnswerLabel = (TextView) findViewById(R.id.textView1);
    mGetAnswerButton = (Button) findViewById(R.id.button1);
    mCrystalBallImage = (ImageView) findViewById(R.id.imageView1);

    mGetAnswerButton.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            String answer = mCrystalBall.getAnAnswer();

            // Update the label with our dynamic answer
            mAnswerLabel.setText(answer);

            animateCrystalBall();
            animateAnswer();
            playSound();

        }
    });
}

private void animateCrystalBall() {
    mCrystalBallImage.setImageResource(R.drawable.ball_animation);
    AnimationDrawable ballAnimation = (AnimationDrawable) mCrystalBallImage.getDrawable();
    if (ballAnimation.isRunning()) {
        ballAnimation.stop();
    }
    ballAnimation.start();
}

private void animateAnswer() {
    AlphaAnimation fadeInAnimation = new AlphaAnimation(0, 1);
    fadeInAnimation.setDuration(1500);
    fadeInAnimation.setFillAfter(true);

    mAnswerLabel.setAnimation(fadeInAnimation);
}

private void playsound() {
    MediaPlayer player = MediaPlayer.create(this, R.raw.crystal_ball);
    player.start();
    player.setOnCompletionListener(new OnCompletionListener() {

        @Override
        public void onCompletion(MediaPlayer mp) {
            mp.release();
        }
    });
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {

    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();
    if (id == R.id.action_settings) {
        return true;
    }
    return super.onOptionsItemSelected(item);
}