Load Level Script Issue

Hey guys hoping someone can help me. I have a levelmanager script that works flawlessly in the opening scene of my game created a cube, disabled the mesh, loaded the script component and set the destination of the next scene. When I go into my second scene and repeat the process my game character walks right through what is supposed to trigger a scene change and nothing happens. For the life of me I cannot figure out why this is. Tried it again in my third scene and also am getting the same result just walks through where the invisible box is and no scene change. I even went back and created a pre-fab of what's working in the first scene and still no luck.

 using UnityEngine;
 using System.Collections;
 using UnityEngine.SceneManagement;
 
 
 public class LevelManager : MonoBehaviour {
     public Transform mainMenu, optionMenu;
 
 
     public void LoadScene(string name) {
         SceneManager.LoadScene(name);
     }
     public void QuitGame() {
         Application.Quit();
     }
 
         }
 
 

I have tried another script you can see below and this one isn't working either.

 using UnityEngine;
 using System.Collections;
 using UnityEngine.SceneManagement;
 
 public class NewBehaviourScript : MonoBehaviour {
 
     public string levelToLoad;
 
     // Use this for initialization
     void Start () {
     
     }
     
     // Update is called once per frame
     void Update () {
     
     }
 
     void OnTriggerEnter(Collider other)
     {
         if (other.tag == "Player")
         {
             SceneManager.LoadScene(levelToLoad);
         }
     }
 }

What i'm trying to achieve is when the player walks through the cube it tosses them into another scene. Any help would be greatly appreciated, total noob to unity.