No collisions being detected

I have two objects that collide with each other, A is moving around the world and B is moved by the user. The collision happens because A bounces off B. However I have:

void OnCollisionEnter(Collision theCollision){
    		Debug.Log (;

in A and this never gets fired.

A is set up like:

B is set up like:

Heh, I made this mistake :wink: