title: Osgviewer cow does not view a cow?
body: <p>I installed <code>OpenSceneGraph 3.0.1</code>using <code>MacPorts</code>. </p>
  
  <p>I've tried <code>osgversion</code> -> <code>OpenSceneGraph Library 3.0.1</code>. I downloaded the <code>OpenSceneGraph-Data</code>.</p>
  
  <p>Everything seems working well than <code>osgviewer cow.osg</code> takes hours without viewing anything !</p>
  
  <p>please I need help ? is there a way to debug ? </p>