Vive controller interaction with gameobject (C#)

I've been trying to script an interaction with a game object so that when the controller and gameobject colliders are touching and the trigger is pressed, a snowball will spawn. Also whilst the trigger is held down the snowball will stay attached to the controller. This script is attached to both controllers.

The game object is a rigidbody which is not kinematic with a box collider which is a trigger. The controllers also have sphere colliders which are triggers (I have also tried it with the controllers not being triggers, the game object not being a trigger and both not being triggers - none of which do anything). Nothing happens when the controller touches the game object, both with the trigger pressed and without. Can anyone help fix this please?

 public class ControllerInteraction : MonoBehaviour {
 
     SteamVR_Controller.Device device;
     SteamVR_TrackedObject trackedobj;
     public GameObject Snowball;
     Rigidbody sbrb;
 
     void Awake () {
             trackedobj = GetComponent<SteamVR_TrackedObject>() ;
                 sbrb = Snowball.GetComponent<Rigidbody>();
     }
     
     void OnTriggerEnter(Collider col){
 
        if (device.GetPressDown(SteamVR_Controller.ButtonMask.Trigger))
             Instantiate(Snowball, gameObject.transform);    
             sbrb.isKinematic = true;
             Snowball.gameObject.transform.SetParent(gameObject.transform);
 
        if (device.GetPressUp(SteamVR_Controller.ButtonMask.Trigger))
           sbrb.isKinematic = false;
           Snowball.gameObject.transform.SetParent(null);
     }
 
 
 }