Play Animation When Player Hit Game Object Colision

I have a horse and game object. When horse hit game object, the animation called “fall” will be played. In here I have control animation of this horse. I’ve been try to use OnTriggerEnter() but the animation still can’t play. Can you help me?

Regards,
Tio

This is my Script

public float MoveSpeed = 5.0f;

void Update () {
	
	if (Input.GetKey (KeyCode.UpArrow)) {
		animation.Play ("run");
		transform.position += transform.forward * MoveSpeed * 0.1f;
	} else if (Input.GetKey (KeyCode.Space)) {
		animation.Play ("jump");
		transform.position += transform.forward * MoveSpeed * 0.1f;
	} else if (Input.GetKey (KeyCode.RightArrow)) {
		animation.Play ("right");
		transform.position += transform.right * MoveSpeed * 0.1f;
	} else if (Input.GetKey (KeyCode.LeftArrow)) {
		animation.Play ("left");
		transform.position += Vector3.left * MoveSpeed * 0.1f;
	} 
}

void onTriggerEnter(Collider kuda){
	if (kuda.gameObject.tag == "Player")
				animation.Play ("fall");
}

you mistyped the funciton name. It is called OnTriggerEnter with a capital O. and also make sure that at least 1 object (either your horse or the other) has a rigidbody component