PhysicsActor won't fall or collide

I am sure I am just missing something.

I created a Sphere using CSG brush, then converted it to a Static Mesh, then converted that to a Physics Actor.
I set it to Wake on Game Start and SImulate Physics, but still nothing happenes. No collisions and no falling.

What am I missing?

Does the mesh have any collision? If it doesn’t it won’t simulate the physics!

This is the correct answer. After you add collision in the Static Mesh editor the physics should function.