Problem with Cycles

I am having a problem with cycles…

So, after modelling for a bit I, press render to see what I have.
For no recognisable reason Cycles just gives me a empty images,
after changing to internal I also get an empty image,
but the view port render mode gives me a render.

Any ideas ?

Have you set object/lights etc to be non renderable in the outliner window (camera icon) ?
Have you set up a composite node network in the node editor ?
Have you added any clips to the sequence editor to over ride the viewport render ?

Post a link to your blend file so others can check it out

The sequence editor ! thx

Hello, I can´t see any shadows from sun in cycles render. Can you help me?
thanks

http://prozone.sk/trava.blend