Help! Why does some balls go throuth my patch?

I'm new to Ogreode, I creat a beizier patch, then I creat some balls, and let them fall on my patch, however some collide with the patch and roll on the patch, but others just go through the patch! And I found that the speed of those which fall through the patch slowdown.

Can someone tell me why?

ps: I've set the gravity.

Try to increase the bouncyness value

I've tried but however large I set the bounceness some balls still fall through my patch. Why?

Well I have not used bezier patches yet, so I cant tell wether this is a bug in the library or if you made a mistake. Are the balls falling through always falling through, so does it depend on the objects or the way they hit the patch? (You could find out by stacking some patches and see if those falling through always fall through)

I just made one patch. I tried many times, not all of them fell through the patch, Just sometimes.

And I also tried to make them fall on the patch the same way. While still some fell through, some didn't.