Object Not Recieving Damage

Ive created an Object that should act as a tower in a spacewars game, it attacks, looks at the target and aims properly and stuff, but it doesn't recieve damage for a reason, I've attached the following script on the object, whats really happening is, that the function OnCollisionEnter isnt even functioning, because the nothing is appearing on the Debug Log:

private int health=20;

`void onCollisionEnter(Collision other)
{
if(other.gameObject.tag==“Bullet”)
{
health-=5;
Debug.Log(health.ToString(),gameObject);
}
}

// Use this for initialization
void Start () {

}

// Update is called once per frame
void Update () {
if(health<=0)
Destroy(gameObject);

}
`

}

Thanks for help.

It is called OnCollisionEnter

ya and your point is? or ur just a troll?

Have you tried any of the Unity tutorials? I know at least one of them has a damage script you can check out.