Collisions or triggers

using UnityEngine;
using System.Collections;

public class XTag : MonoBehaviour {
    public GameObject xTag;

	// Use this for initialization
	void Start () {
	
	}
	
	// Update is called once per frame
	void Update () {
	
	}
    void onTriggerEnter(Collider col)
    {
        if (col.gameObject.name == "R0C0")
            Debug.Log("X");
    }
}

I have tried using onTriggerEnter and onCollisionEnter but nothing is working for this situation. Am I missing something on the gameobject? What do I need to have this print?

OnTriggerEnter not onTriggerEnter & OnCollisionEnter not onCollisionEnter . & make sure your objects have collider component