Need help again - dynamic objects collisions

I am stuck again with BGE. I have simple scene: three cubes and empty. Red cube is parented to green cube. Yellow cube is parented to empty. Empty has action (floating up-down). Green cube has always senser attached to motion - moving green cube and his child - red cube towards to yellow cube. Red cube has collision sensor (property “1”) attached to motion actuator (rotation on z axis). Yellow cube has property called “1”. Both yellow and red cubes are dynamic objects with “actor” option activated. So when red cube is colliding with yellow cube nothing happens. I want red cube rotating on z axis. But it doesn’t working and I don’t know why. Here is blend.


Collision.blend (440 KB)

on the red cube set physics to sensor.

That’s worked! Thank you.