Bug on first play or after building

Hi, I'm working on a project with ARToolkit (a package for augmented reality) I have a problem with my project : it works fine as many times as I want until I build an APK for android. Just after that, it doesn't work on Unity (and it doesn't work on the application installed from the apk) My scene is a basic scene of ARToolkit that works perfectly. The only modification I made was to attach a script to create manually gameObjects. Here is the script :

 using UnityEngine;
 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine.UI;
 using UnityEngine.EventSystems;
 
 public class MarkersCreator : MonoBehaviour {
     const int N=10;
 
     string[] names=new string[N];
     ARMarker[] markers=new ARMarker[N]; //ARMarker is a GameObject of ARToolkit
     ARTrackedObject[] tracked = new ARTrackedObject[N]; //ARTrackedObject is a GameObject of ARToolkit
 
 
 
 
     // Use this for initialization
     void Start () {
         GameObject root = GameObject.Find ("Scene root"); //This GameObject exists in my scene
 
         names [0] = "name0";
         names [1] = "name1";
         names [2] = "name2";
         names [3] = "name3";
         names [4] = "name4";
         names [5] = "name5";
         names [6] = "name6";
         names [7] = "name7";
         names [8] = "name8";
         names [9] = "name9";
         
         
         for (int i = 0; i < N; i++) {
             markers [i] = gameObject.AddComponent<ARMarker> ();
             markers [i].Tag = "marker"+i.ToString();
             markers [i].MarkerType = MarkerType.NFT;
             markers [i].NFTDataName = names [i];
 
             GameObject markerscene = new GameObject ("MarkerScene"+i.ToString());
             markerscene.layer = 9;
             markerscene.transform.parent = root.transform;
             markerscene.transform.localRotation = Quaternion.Euler (Vector3.zero);
 
 
 
 
 
             tracked [i] = markerscene.AddComponent<ARTrackedObject> ();
             tracked [i].MarkerTag = markers [i].Tag;
 
             Debug.Log ("cube créé");
 
             GameObject cube = GameObject.CreatePrimitive (PrimitiveType.Cube);
             cube.layer = 9;
             cube.transform.parent = markerscene.transform;
             cube.transform.localPosition = new Vector3 (0, 0, -0.02f);
             cube.transform.localRotation = Quaternion.Euler (Vector3.zero);
             cube.transform.localScale = new Vector3 (0.04f, 0.04f, 0.04f);
 
 
         }
 
     }
 
 }
 

I also noticed that it doesn't work when I open Unity for the first and press play. I have to remove my script and attach again and it works (I have to make the same manipulation after building an apk).

I really don't understand. It must come from my script but why does it work sometimes ?

Did it happen yet to someone ? Does anyone has a clue ?

Thank you for your answers.

Ilyès