Doesn't collide! HELP!!!

dropbox.com/s/koa4r3pqz0vovfa/ground3.egg
The above is a egg labyrinth I created similar to the one in sample ball-in-maze just a little more complicated.
dropbox.com/s/osvf1ur798v9swh/ball.py
And I used this code, which is basically just the ball-in-maze code to try to make it work on my model.
However, even though I can see all the collision surfaces highlighted using cTrav.showCollisions(render), the ball just won’t bounce back! Can anybody help me with that??

Thank you so much in advance!!!