Loading Sene problem

So Im making my first “minigame” I guess, So when i hit the finish line this gui pops up, on one of the buttons it says next(thats for next level). Currently I have three scenes: Level1, Level2, Level3. I can press next and get to Level2 but it doesn’t work on Level3 (I Have a different script for each level)

Nextscript from 1 to 2
using UnityEngine;
using UnityEngine.UI;
using UnityEngine.SceneManagement;

public class NextScript : MonoBehaviour {

    public Button NextBtn;
    public Text NextBtnTxt;

    // Use this for initialization
    void Start () {
        NextBtn.onClick.AddListener(onClicked);
	}
	
	// Update is called once per frame
	void onClicked () {
        NextBtn.enabled = false;
        NextBtnTxt.enabled = false;
        SceneManager.LoadScene("Level2", LoadSceneMode.Single);
        
	}
}

NextScript from 2 to 3

using UnityEngine;
using UnityEngine.UI;
using UnityEngine.SceneManagement;


public class NextScriptLvl2 : MonoBehaviour {

    public Button NextBtn1;
    public Text NextBtnTxt1;

    // Use this for initialization
    void Start () {
        NextBtn1.onClick.AddListener(onClicked1);
	}
	
	// Update is called once per frame
	void onClicked1 () {
        NextBtn1.enabled = false;
        NextBtnTxt1.enabled = false;
        SceneManager.LoadScene("Level3", LoadSceneMode.Single);
        
	}
}

again First one works great, the second one doesn’t

Reducing code duplication is always a good practive to avoid dealing with errors you have to correct in multiple places. In this case, you can make the level name a public string variable and use the same script in every scene, typing the next level name in the inspector. Despite that fact, either the scene is not spelled right, the scene looks identical to the other and you just THINK it did not work, or you forgot to add the scene to the build settings.

The scenes are different and they are all in the build settings, but I will try your suggestion