I'm trying to make a machine-game, where the user can place springs, fans, treadmills etc on the screen to make objects interact with them. So I need to have a lot of "create new object" events for physics objects.
As a test (attachment) to point out the problem, I made this simple program. There's a fan under the left ball that blows air upwards, so the ball keeps floating. When you click the left mouse button, a fan including the fan physics object appears for the right ball.
And it does create the new fan, as an indicator moves to where the new fan object now is. However, the fan is completely inactive.
I've tried to switch on the fan, set the strength and angle of air every time the even triggers. That also doesn't help.
 I've noticed just now it does work for visible physics objects like ropes, but not for invisible forces like fans or treadmills.