For loop not working

Question

  //from com VBA call below this loop worked fine with array  
  for (int i = 0; i < myLength; i++)
   {
      string[] ar = Array.ConvertAll((object[])o1[i], x => (string)x);
      List<string> st = new List<string>(ar);
      foreach (var x in st)
         str += "*" + x + "*";
    }

  //from com VBA call below this loop not worked fine with array 

 

   for (int i = 0; i < myLength; i++)
   {
      string[] stt = (string[])s4[i];
      for (int p = 0; p< stt.Length; p++)
      {
         val += stt[p];
      }
    }