Sphere and Cube collision won't work,Sphere vs Cube collision won't work

I am trying to build a simple unity 3D game using a sphere and several cubes.
As you can see in the image when the sphere collides with any cube, the game is suppose to finish.
Please be advised that OnCollisionEnter and OnTriggerEnter functions aren’t working. Thanks.

,Hello Guys,

Did you add rigidbody to the sphere?