simple roll a ball game - ball slips threw ground

Hey folks. so iam working on this game:



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


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
and use gravity

the plane has a boxcollider with a thickness of Y:2. but also change this to 20 or more doesn't solved the problem.

the ball has not movement script. its just a rigidbody. but the ground gets tilted based on where you click

Code (CSharp):

1.  if (Input.GetMouseButton(0)) {
2.              RaycastHit hit;
3.              Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
4.              if (Physics.Raycast(ray, out hit, mask.value))
5.                  if (hit.rigidbody != null)
6.                      hit.rigidbody.AddForceAtPosition(ray.direction * pokeForce, hit.point);
7.            
8.            
9.          }

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?