Trouble with Common Assets on ubuntu 14.04


I wanted to use the PSSMRendering and got an Error on using some Shadow-File from the Common Assets file.
Later I tried to add a sky and got a similar Error Message:

Uncaught exception thrown in Thread[LWJGL Renderer Thread,5,main]
com.jme3.asset.AssetLoadException: An exception has occured while loading asset: Common/MatDefs/Misc/Sky.j3md
at com.jme3.asset.DesktopAssetManager.loadAsset(

So I believe something with my Common files is wrong.

I am using JMonkeyEngine with Ubuntu 14.04 and just did a normal Installation.
Did I forget to install some extra packages?

By the way I can’t use the scene builder, too.

Oh, I was wrong with the scene builder. This thing works.