public string GetNextFileName(string currentName)
            {
                int index = 0;
                Regex _reg = new Regex(@"(?<=\()\d+?(?=\))");
                Match m = _reg.Match(currentName);
                if (_reg.IsMatch(currentName))
                {
                     index = int.Parse(m.Value);
                     index++;
                }
                return index.ToString();
            }