title: TypeError: Cannot call method "show" of null
body: <p>I see some sample code from other site and i see this but when i paste and run it's  have an error "TypeError: Cannot call method "show" of null. (line 5, file "</p>
  
  <pre><code>function hello() {
  var ss = SpreadsheetApp.getActiveSpreadsheet();
  var app = UiApp.createApplication().setTitle('title Dude');
  app.add(app.createLabel('Hello World'));
  ss.show(app);
  }
  </code></pre>
  
  <p>Can some help me with this? </p>