why doesn't my triggers work?

SO this is a basic nav script. I want it so when capsule(player) is "deployed" from one end of a level and goes towards a target, and when it gets close enough to a target is should stop and then I'll run other functions. The problem is that I can't even get the triggers to work. It shouldn't be calling my test function a bunch of times. Just the one time. public Transform target; public Transform enemy;

 NavMeshAgent nav;

 // Use this for initialization
 void Start () {
     nav = GetComponent<NavMeshAgent> ();
 }
 
 // Update is called once per frame
 void Update () {
     move ();
 }
 void move()
 {
     nav.SetDestination (enemy.position);
     /*Vector3 fwd = transform.TransformDirection(Vector3.forward);
     if (Physics.Raycast (transform.position, fwd, 10)) {

     }*/
 }

 void OnTriggerEnter(Collider other) {
     print ("Atttack()");
 }