Android Problem displaying message

Hi. I have followed the instructions at the following link to display a message on a button
click in my first Android app but when I click the button, nothing happens.
Have I done something wrong? Thanks

http://developer.android.com/training/basics/firstapp/starting-activity.html

package co.webexcel.myfirstapp;

import android.annotation.SuppressLint;
import android.annotation.TargetApi;
import android.app.Activity;
import android.content.Intent;
import android.os.Build;
import android.os.Bundle;
import android.support.v4.app.NavUtils;
import android.view.MenuItem;
import android.widget.TextView;

public class DisplayMessageActivity extends Activity {
      //Additionally, you must add the @SuppressLint("NewApi") tag to the
      //onCreate() method to avoid lint errors.
      @SuppressLint("NewApi")
      @Override
      protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_display_message);
            // Make sure we're running on Honeycomb or higher to use ActionBar APIs
          // Get the message from the intent
          Intent intent = getIntent();
          String message = intent.getStringExtra(MainActivity.EXTRA_MESSAGE);

          // Create the text view
          TextView textView = new TextView(this);
          textView.setTextSize(40);
          textView.setText(message);

          // Set the text view as the activity layout
          setContentView(textView);
            //setupActionBar();
      }

      /**
       * Set up the {@link android.app.ActionBar}, if the API is available.
       */
      @TargetApi(Build.VERSION_CODES.HONEYCOMB)
      private void setupActionBar() {
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
                  getActionBar().setDisplayHomeAsUpEnabled(true);
            }
      }



      @Override
      //this handles the behavior for the action bar's Up behavior
      public boolean onOptionsItemSelected(MenuItem item) {
            switch (item.getItemId()) {
            case android.R.id.home:
                  // This ID represents the Home or Up button. In the case of this
                  // activity, the Up button is shown. Use NavUtils to allow users
                  // to navigate up one level in the application structure. For
                  // more details, see the Navigation pattern on Android Design:
                  //
                  // http://developer.android.com/design/patterns/navigation.html#up-vs-back
                  //
                  NavUtils.navigateUpFromSameTask(this);
                  return true;
            }
            return super.onOptionsItemSelected(item);
      }

}