The boss bullet won't collide with anything

Hi every one.

I’m a game development student and lately I made a tech demo for college.
It is a 2D action platformer heavily inspired by Mega Man.

I came across this problem where the boss bullet won’t collide with anything. It should collide with the walls but it isn’t. :frowning:

I’ll be very grateful if someone can spot my mistake on the code.

using UnityEngine;
using System.Collections;

public class BossBullet : MonoBehaviour {

	Transform myTransform;
	Vector3 direction;
	public float speed = 100f;
	public int myDamage = 1;

	void Awake()
	{
		myTransform = transform;
	}

	public void Setup(Vector3 newDirection, float newSpeed)
	{
		direction = newDirection;
		speed = newSpeed;
	}


	void FixedUpdate () 
	{
		myTransform.position += direction * Time.fixedDeltaTime;
	}

	void OnTriggerEnter(Collider other)
	{
		if (other.tag == "Character") 
		{
			//Make Character take damage
		} 
		if(other.tag == "Wall")
		{	
			Debug.Log("Hit Wall!");
			Destroy(gameObject);	
		}

	}
}

are you sure that you want to use OnTriggerEnter? maybe use OnCollisionEnter(Collision other)

I changed it to OnTriggerEnter2D (Collider2D other) and worked.
Looks like I have to use the 2D variants of the classes.