Items from Suggestion list of textBox can't be selected by down key. Only 1st is selected when down key is pressed. How to select other item other than 1st item.

 private void ItemTextBox_TextChanged(object sender, EventArgs e)
{

     try
    {
    string keyword = ItemDescTextBox.Text.TrimStart();
     SqlCommand cmd = new SqlCommand("SELECT ItemDescription FROM ItemsDetail WHERE ItemDescription LIKE '%" + keyword + "%'", con);
     cmd.CommandType = CommandType.Text;
     SqlDataReader dr = cmd.ExecuteReader();

     List<string> ItemSuggestionsList = null;

     if (dr.HasRows)
     {
         ItemSuggestionsList = new List<string>();
         while (dr.Read())
         {
             string row = "";
             row = Convert.ToString(dr["ItemDescription"]);
             ItemSuggestionsList.Add(row);
         }
         ItemSuggestionsList.TrimExcess();
     }

     if (dr != null)
     { dr.Close(); }

        string[] sugs = ItemSuggestionsList.ToArray();
        ItemSuggestionsList.Clear();

        //Create and initialise object source for AutocompleteStringCollection
        AutoCompleteStringCollection source = new AutoCompleteStringCollection();
        source.AddRange(sugs);
        ItemDescTextBox.AutoCompleteCustomSource = source;
        ItemDescTextBox.AutoCompleteMode = AutoCompleteMode.Suggest;
        ItemDescTextBox.AutoCompleteSource = AutoCompleteSource.CustomSource;
    }
    catch (Exception ex)
    {
        label1.Text="ex source: " + ex.Source +
                          "\nex msg: " + ex.Message +
                          "\nex stk trace: " + ex.StackTrace;
    }

 }