I get the panel to work but I get this error:

I get the panel to work but I get this error:
  • Johannes Luebke(megohannes) replied
    File "\ui_panle_simple.py", line 16, in draw KeyError: 'bpy_prop_collection[key]: key "props" not found'
  • Johannes Luebke(megohannes) replied
    ok restarting Blender and running the same script again fixed that. I don´t understand?