index was out of range when executing datareader

I'm trying to connect to Mysql Database using UWP.

      objConn.Open();
      MySqlCommand cmd = new MySqlCommand("select city_ID,city_Name from cities", objConn);
      MySqlDataReader dataReader = cmd.ExecuteReader(); // <------ Here

      int i = 0;
      while (dataReader.Read())
      {
         StudentsList.Items.Add("");
         StudentsList.Items.Add(dataReader.GetString(1).ToString());
         i++;
      }
      objConn.Close();

when I execute the code an error appears:

index was out of range. must be non-negative and less than the size of the collection. Parameter name:startIndex

The error occurs when app reach this line:

MySqlDataReader dataReader = cmd.ExecuteReader();