Scene changing problem

So I've been trying to figure out how to switch from one scene to another within Unity 5.3, but I'm having trouble when I call upon the function that is supposed to load the next scene. The scene doesn't change and an error pops up saying that:

Scene 'Scenes/Main Scene.unity' (-1) couldn't be loaded because it has not been added to the build settings or the AssetBundle has not been loaded. To add a scene to the build settings use the menu File -> Build Settings

I've tried changing the name for the scene in the inspector and I've added the scene into the build settings, and I still am having trouble. To be completely honest, though, I don't know what the problem is. I've never dealt with scenes (normally, I just make one scene). So, I'll just provide as much information I can and hope that the Unity Community can help me understand why the scene isn't changing and the above error is appearing.

Here's my script for changing scenes:

 using UnityEngine;
 using System.Collections;
 using UnityEngine.UI;
 using UnityEngine.SceneManagement;
 
 public class MenuScript : MonoBehaviour {
 
     public Canvas quitMenu;
     public Button startText;
     public Button exitText;
     [SerializeField]
     string m_MainLevel = string.Empty;
 
 
     void Start () {
         quitMenu = quitMenu.GetComponent<Canvas> ();
         startText = startText.GetComponent<Button> ();
         exitText = exitText.GetComponent<Button> ();
         quitMenu.enabled = false;
     }
 
 
     public void ExitPress()
     {
 
         quitMenu.enabled = true;
         startText.enabled = false;
         exitText.enabled = false;
 
     }
 
     public void NoPress()
     {
         quitMenu.enabled = false;
         startText.enabled = true;
         exitText.enabled = true;
     }
 
     public void StartLevel(){
         SceneManager.LoadScene (m_MainLevel);
     }
 
     public void ExitGame()
     {
         Application.Quit ();
     }
 }
 

The scene that I'm trying to get to is named Main Scene.

Within the inspector, I have defined Main Level as Scenes/Main Scene.unity, which is what I copied from the build settings when I added the scene to the settings.

I have not messed around with AssetBundles and I have no idea what they are.

If you need any additional information, please let me know!