onCollisionEnter not called

I know this has been asked plenty of times. But I still cant seem to get this working.
I have a 3D plane as the ground and a player (mocap, from the Unity examples). The player is a rigid body and not kinematic and has a box collider attached to it. The plane is a rigid body and is kinematic and has a box collider attached to it. I’ve written onCollisionEnter for both the player and ground script. But both aren’t getting called.

void onCollisionEnter(Collision col)
{
    Debug.Log("Player");
}

Is there something else I need to do for the collision to get called?

Thanks in advance.

It has been asked plenty of times. And it’s been answered plenty of times too. And here it is again:

The method is called OnCollisionEnter, not onCollisionEnter.