PINBALL: Ball colliding problems

Before you read, here is a video about my problem:

VIDEO

The video shows from the top, but this is a 3d game.

The ball sometimes collide with the walls, sometimes not, and sometimes it goes into the flippers or other object, as you can see in the video at 0:08 or 0:14. The half of the ball is in the floor as well, so it doesn't roll at the top of it. Picture:

• The blue walls and the flippers have mesh colliders.

• The ball has sphere collider.

• The floor has box collider.

• The ball and the flippers have rigidbody attached, set up: Interpolate, and continous dynamic detection.

• Time setup is: fixed timestep= 0,01; max= 0,33; time scale=1 .

Thanks for yous helps!!!

(Sorry for language problems.)