OnCollisionEnter with rigidbody does not work?

I’ve created an arrow and a wall, both having BoxColliders. Only the arrow has a Rigidbody, attached and neither collider is marked as isTrigger. The arrow’s script includes an onCollisionEnter function:

void onCollisionEnter(Collision other){
	if(other.gameObject.tag != "animal"){
		Destroy (gameObject);

The OnCollisionEnter function, however, is never called. What am I doing wrong? The arrow stops moving after it hits the cube, and turning on isKinematic makes it pass through.

try naming it OnCollisionEnter ( capital O at the start ). The method names have to be exact to make it work.