Problem with Mesh Collider - Cup

[kasztan165]

Hey guys!
So I made a glass, i have nice structure to mesh collider and it’s going like that:

I add rigidbody, mesh collider and add a basic structure of my cup.
What I want is to drop ball into this cup. But it’s stuck onto the top of them.
Like that:

So my mesh is looking good, why Unity don’t make a full collider? Why is closed from top?
Any idea?

[kasztan165]

Thanks for your help this is lightend few things for me.
And screen to show how I implementing this: