Bouncing ball tutorial - Ball goes through the floor.

I am running through the tutorials and I am having an issue with the bouncing ball tutorial. I have the Robot Lab downloaded and I can load the empty scene just fine. I add the prop_samoflange and attach a rigidbody and sphere collider to it. Then I run it and it falls right through the floor. Did I miss something from the video or did he do something before hand and not say what? Here is a link to the tutorial page: 1

I had the same problem. I think something is missing in the empty scene. I fixed it by adding a mesh collider component to floor_007.

Just to note, it does seem the robotLab environment in the Empty scene is messing its mess collider. The answer proposed by Marzel will work but only for floor 7, the correct approach should be adding a mess collider to the whole environment:

  1. Select env_robotLab_static under Static Objects
  2. Add Component → Physics → Mess Collider
  3. Click the circle beside Mesh property to change it, and locate env_robotLab_collision_001