Help setting dialog box to true

Hello, can you help me to set active to true my dialogue box here i don't know what's the problem. thank you here's my code.

 using UnityEngine;
 using System.Collections;
 using UnityEngine.UI;
 
 public class DialogueHolder : MonoBehaviour
 {
     public GameObject dbox;
     public Text txt;
 
     // Use this for initialization
     void Start()
     {
         dbox.SetActive(false);
     }
 
     // Update is called once per frame
     void Update()
     {
 
         if (dbox && Input.GetKeyDown(KeyCode.Return))
         {
             dbox.gameObject.SetActive(false);
         }
     }
 
     void onTriggerEnter2D(Collision2D coll)
     {
         if (!dbox)
         {
             if (coll.gameObject.tag == "Player")
             {
                 dbox.gameObject.SetActive(true);
             }
         }
     }
 }