Have GUI element enter screen on trigger

I am currently working on a script that is attached to my player character game object which should cause a UI element to enter the screen when they enter a 2D circle collider of an NPC game object. So far I have not even been able to get the script to detect wether the player has collided with the NPC's proximity collider.

 public class ConvoRegulator : MonoBehaviour {
 
 
     public GameObject ConvoUI;
     public GameObject Player;
 
     Animator ani;
 
     void Awake () {
         ani = ConvoUI.GetComponent<Animator> ();
     }
 
     public bool IsInside = false;
 
     void OnTriggerEnter(Collider collider)
     {
         IsInside = true;
         if(collider.tag == "NPC") // this string is your newly created tag
         {
             ani.SetTrigger ("Enter");
             IsInside = true;
         }
     }
 
     void OnCTriggerExit(Collider collider)
     {
         IsInside = false;
         if(collider.tag == "NPC") // this string is your newly created tag
         {
             ani.SetTrigger ("Exit");
             IsInside = false;
         }
     }
 }

This will be used to bring up a box with dialog options when the player approaches and NPC and lower the box back off screen when the player leaves. Any suggestions on how to get this to work or how to change it are greatly appreciated.