Problem with shadows on the moveable objects - need help!

I have a problem with shadows, which should appear on the models of leaves but it don’t. I attached two screens -one shows settings my movable objects ( leaves modeled and boned in 3d studio max) and the screen of my direct light settings .
As You see, the leaves drop nice shadow and everything is correct with them but when I change their possition and they land under the wooden desk, the should get shadow from the desk…

Any tips/ sollution?
Many thanks!

thanks for Your answer.
When look a bit closer to this I can see that the shadow exists, but why so bright?