button.onClick.AddListener(method); NOT Working

So I'm creating a very basic menu with 3 buttons. I had the buttons working earlier today to the point that they would do what they should have. Unfortunately, because of some tweaking I did, the onClick function doesn't seem to be working for me. I would love some insight, thank you!

Code: using System.Collections; using System.Collections.Generic; using UnityEngine; using UnityEngine.UI;

 public class PauseUI : MonoBehaviour {
     private Component[] buttons, screens;
     private Canvas pauseMenu;
     private Button resumeGame, exitGame;
     private Camera characterCam, pauseCam;
     void Start () 
     {
         characterCam = GameObject.Find ("MainCamera").GetComponent<Camera>();
         pauseCam = this.GetComponent<Camera> ();
         buttons = GetComponentsInChildren<Button> ();
         screens = GetComponentsInChildren<Canvas> ();
         foreach (Button button in buttons) {
             if (button.name == "ResumeGame") {
                 resumeGame = button;
             }
             if (button.name == "ExitGame") {
                 exitGame = button;
             }
         }
 
         foreach (Canvas canvas in screens) {
             if (canvas.name == "PauseMenu") {
                 pauseMenu = canvas;
             }
         }
         characterCam.enabled = true;
         pauseCam.enabled = false;
         pauseMenu.enabled = false;
 
     }
     
     // Update is called once per frame
     void Update () 
     {
         if (Input.GetKeyDown (KeyCode.Escape)) {
             pauseMenu.enabled = true;
             characterCam.enabled = false;
             pauseCam.enabled = true;
         }
         resumeGame.onClick.AddListener (ResumeGame);
     }
 
     void ResumeGame(){
         Debug.Log ("ResumeGame has been clicked!");
         pauseMenu.enabled = false;
         characterCam.enabled = true;
         pauseCam.enabled = false;
     }
 }