Softbody simulation with non primitive objects - A rolling ball and a slide

Hi, 

I am trying to build a soft body simulation where a soft body ball falls and rolls in a slide. 

Somehow it does not seem to work!

1) Soft body simulation works if I use simply a plane.

2) Here I used modified mesh out of half circle and out of a plane.

3) Applied solidify modifier.

4) closed mesh

5) And applied collision.

But still the soft ball penetrates upper surface of the mesh.

Can somebody help me?