title: jmonkey shows blackscreen with blender models
body: <p>So I build a model of a tank in blender which I implemented later on in jmonkey with a spatial. But when I gave the model texture, materials and morde detail, jmonkey responds with an error "NullPointerExeption" and closes the test application which ended as a blackscreen before. </p>
  
  <p>Is anyone familiar with this problem?</p>