LogCat not displaying TAG "SMS"

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    Log.e("SMS","Hello World");   //not showing
    Log.v("SMS","Hello World");   //not showing
    Log.i("SMS","Hello World");   //not showing
    Log.d("SMS","Hello World");   //not showing

    Log.i("sms","Hello World");   //showing
}

Why the Logging in the Logcat is not working for some line in the above code??