Saving data in to files (Android)

Hey, I'm trying to save information on files using these methods, here's the code:

 using System.IO
 
 public class scoreFile
 {
     private int[] level;
     private bool[] completed;
     private float[] completionTime;
 
     private string[] scores;
 
     private string fileName;
 
 
     //This class stores information for each of the levels.
     public scoreFile(int num)
     {
         fileName = "scores.txt";
 
         try
         {
 
             if (!File.Exists(fileName))
             {
 
                 level = new int[num];
                 completionTime = new float[num];
                 completed = new bool[num];
                 scores = new string[num];
 
                 Debug.Log("Opened file!");
 
                 for (int i = 0; i < num; i++)
                 {
                     level[i] = i + 1;
                     completionTime[i] = 0;
                     completed[i] = false;
 
                     scores[i] = level[i] + " " + 0 + " " + completionTime[i];
                 }
 
                 Debug.Log("About to write into file!");
                 File.WriteAllLines(fileName, scores);
             }
 
             else
             {
                 Debug.Log("File is exist! Loading!");
                 loadFile();
             }
         }
 
         catch (System.Exception e)
         {
             Debug.Log(e);
         }
     }
 
     public bool isComplete(int i) { return completed[i]; }
     public int levels(int i) { return level[i - 1] + 1; }
     public float timeScore(int i) { return completionTime[i]; }
 
 
 
     public void loadFile()
     {
         Debug.Log("Reading");
         string[] levelsInfo = File.ReadAllLines(fileName);
 
         int num = levelsInfo.Length;
 
         level = new int[num];
         completionTime = new float[num];
         completed = new bool[num];
 
         for (int i = 0; i < num; i++)
         {
             //Debug.Log(levelsInfo[i]);
             string str = levelsInfo[i];
             level[i] = (int)int.Parse(str.Substring(0, 1));
             int f = int.Parse(str.Substring(2, 1));
             if (f == 0)
                 completed[i] = false;
             else
                 completed[i] = true;
             completionTime[i] = (float)float.Parse(str.Substring(4));
         }
     }
 }

It works great on Unity3D, but doesn't on my android mobile device (Nexus 4) is it because im using TXT extension? I don't understand whats the issue.