title: Why doesn't my Send button work?
body: <p>I've created my first app, step by step, as described on</p>
  
  <p><a href="http://developer.android.com/training/basics/firstapp/starting-activity.html" rel="nofollow">http://developer.android.com/training/basics/firstapp/starting-activity.html</a></p>
  
  <p>According to this page, after clicking the button, there should appear a default "Hello world" layout, respectively the message typed in the text field.</p>
  
  <p>Unfortunately, none of them appears at all. Absolutely nothing happens. Why?</p>
  
  <p>Thanks in advance...</p>