simple roll a ball game - ball slips threw ground

Hey folks. so iam working on this game:

59996-59993-dribbble.png

and its almost done. but i have one last bug left:

http://postimg.org/image/h5eiae7j7/

as you can see, the ball is slipping threw the plane. i think its related to my global gravity setting. its Y: -600
but when i change it to something more normal like -10. the ball is just super slow or dosent move at all anymore? the rigidbody of the ball is:
mass: 20 - Drag: 0 - Angular Drag: 0,05

but also changing these values to something like mass 200 or 2 doesn’t give me the same grip anymore. does anybody have an idea whats wrong?

Not exactly sure, but this looks like an transform.rotation movement, which is anything but working well with colliders. On another note, you can move the ball easier by changing the formula for the addForce, I usually go by multiplying mass and an speedFactor. When the addForce is to low your object nearly wont move.