3DS Max Rendering Assignment

Recently, i still busy rendering the 3ds assignment that I've been working on. The whole model is not done by me, the task of this assignment is to choose one of the 3D models from this website and then later i find texture photos to map on the models... and learnt some tutorials from youtube about rendering the leaves on the trees and grass.

But I have this one problem that I don't know what gone wrong. The grass seems not shadows or shadow... I already put the lighting, free light and target light. I put lighting before i add the grass because i want to see the result of lighting so that i can adjust to the correct one before i add the grass, so that I won't need to wait longer time to see the rendered image with lighting and grass

hope anyone can tell me what's wrong, or nth actually gone wrong? is it because the grass is short that very hard to have shadow?=.=