title: Magento custom admin module is blank
body: <p>I've create a custom admin module but i can't put a content in it, it always is blank
  i'm trying with a simple code for test, but nothing seem to work</p>
  
  <pre><code>public function indexAction()
  {
      $this-&gt;loadLayout();
  
      $this-&gt;_addContent($this-&gt;getLayout()-&gt;createBlock('adminhtml/template')-&gt;setTemplate('uhmaadmin/contactos.list.phtml')-&gt;toHtml());
      $this-&gt;renderLayout();
  }
  </code></pre>
  
  <p>an in the .phtml</p>
  
  <pre><code>echo 'hello world';
  </code></pre>
  
  <p>but doesn't print nothing, if a make an error in the phtml, the system crash, it means that its getting the file, but, what i'm i missing
  please, help</p>