The Quad with DrawElements Tutorial - Quad not rendered

[amaridev]

Hi,
I have a problem here and hope you guys can help me.
I wrote a program in legacy openGL which I am trying to refactor now to a newer openGL Version. But somehow I am not able to render anything. Display Window starts, clear color gets set. But thats it. No objects.
So far I was unable to debug and find the error, so I went for the most simple tutorial I found and tested a basic setup.

I took the code from here: http://wiki.lwjgl.org/wiki/The_Quad_with_DrawElements
And for some reasons I can not explain to myself I have the exact same problem here as I had in my own program. I get the canvas with the blue background. But the quad is not displayed.

I used lwjgl 2.9.2. Do you have an idea why the code from the tutorial does not work for me?
If I can figure that out, I'll may be able to fix my own code.

best regards