Android - can't read TXT files from SDcard on real machine?

When I run the code bellow in the virtual android (1.5) it works well, TextSwitcher shows first 80 chars from each txt file from /sdcard/documents/ , but when I run it on my Samsung Galaxy i7500 (1.6) there are no contents in TextSwitcher, however in LogCat there are FileNames of txt files.

My Code:

      public void getTxtFiles(){
 //Scan /sdcard/documents and put .txt files in array File TxtFiles[]
    String path = Environment.getExternalStorageDirectory().toString()+"/documents/"; 
    String files;
    File folder = new File(path);
    if(folder.exists()==false){if (!folder.mkdirs()) { 
        Log.e("TAG", "Create dir in sdcard failed"); 
        return; 
   }} 
    else{
    File listOfFiles[] = folder.listFiles(); 

    for (int i = 0; i < listOfFiles.length; i++) 
    {

     if (listOfFiles[i].isFile()) 
     {
     files = listOfFiles[i].getName();
         if (files.endsWith(".txt") || files.endsWith(".TXT"))
         {
            if((files.length()-1)>i){resizeArray(TxtFiles, files.length()+10);}
             TxtFiles[i]=listOfFiles[i];
             System.out.println(TxtFiles[i]);
         }
          }
       }}
    }


 private void updateCounter(int Pozicija) {
 if(Pozicija<0){Toast.makeText(getApplicationContext(), R.string.LastTxt, 5).show();
 mCounter++;}
 else if(TxtFiles[mCounter]!=null){
  TextToShow = getContents(TxtFiles[mCounter]);
  if(TextToShow.length()>80)TextToShow=TextToShow.substring(0, 80);
  mSwitcher.setText(TextToShow);
  System.out.println(Pozicija);
  }
 else mCounter--;
 }

   static public String getContents(File aFile) {
    //...checks on aFile are elided
    StringBuilder contents = new StringBuilder();

    try {
      //use buffering, reading one line at a time
      //FileReader alwa开发者_C百科ys assumes default encoding is OK!
      BufferedReader input =  new BufferedReader(new FileReader(aFile));
      try {
        String line = null; //not declared within while loop
        /*
        * readLine is a bit quirky :
        * it returns the content of a line MINUS the newline.
        * it returns null only for the END of the stream.
        * it returns an empty String if two newlines appear in a row.
        */
        while (( line = input.readLine()) != null){
          contents.append(line);
          contents.append(System.getProperty("line.separator"));
        }
      }
      finally {
        input.close();
      }
    }
    catch (IOException ex){
      ex.printStackTrace();
    }

    return contents.toString();
  }

And I am able to write contents of those files though LogCat!

Any ideas?

---

Problem solved: Android is based on Linux kernel and it has file permissions. I guess my app didnt have permissions over those files in /sdcard/documents/.