Not able to get proximity sensor's values in android

Can someone provide an example as to how to use the proximity sensor? I tried to use it the same way as other sensors, but it's not working.

This is the code snippet i have been using:

 final SensorManager mSensorManager;
 final Sensor mproximity;

mSensorManager = (SensorManager)getSystemService(SENSOR_SERVICE);
mproximity =  mSensorManager.getDefaultSensor(Sensor.TYPE_PROXIMITY);

mSensorManager.registerListener(new SensorListener(){

public void onAccuracyChanged(int arg0, int arg1) {
   // TODO Auto-generated method stub
   Toast.makeText(test.this,"proximity sensor accu ", Toast.LENGTH_SHORT).show();
}

public void onSensorChanged(int arg0, float[] arg1) {
   // TODO Auto-generated method stub
   Toast.makeText(test.this,"proximity sensor ", Toast.LENGTH_SHORT).show();
}

}, Sensor.TYPE_PROXIMITY, 1);

Please tell me where I am going wrong.