How do I get my time manager script that I wrote in C# to switch to my game over scene in unity 5

I have built a scene in unity called game over which works when the timer hits 0 in my time-manager script, it works on the computer when the timer hits 0 unity changes scenes but this is a mobile application that needs to work on mobile and I have tried a few different things but it just goes to negative numbers once it hits 0 when playing on a mobile device. Does anyone know how to get the timer to change scenes so it will work on mobiles ? (The issue/problem is on lines 30-31 please help.

using UnityEngine;
using System.Collections;
using UnityEngine.UI;

public class TimeManager : MonoBehaviour {

	public float startingTime;

	private float countingTime;

	private Text theText;

	public LopterMovement player;

	public string startLevel;

	// Use this for initialization
	void Start () {
		countingTime = startingTime;

		theText = GetComponent<Text> ();

		player = FindObjectOfType<LopterMovement> ();
	// Update is called once per frame
	void Update () {
		countingTime -= Time.deltaTime;

		if (countingTime <= 0) {

		theText.text = "" + Mathf.Round (countingTime);

	public void ResetTime()
		countingTime = startingTime;

Your issue is unrelated to platform, neither the way you count.

If you say it goes negative numbers then it is not related to ResetTime either.

Most likely you forgot to add startLevel scene to Build Settings => Scenes in build, or you forgot to assign startLevel variable, as it is never assigned in the script itself.