请求帮助

using System;using System.Collections.Generic;using System.Linq;using System.Text;

namespace 分割字符串{    class Program    {        static void Main(string[] args)        {            string str1 = "河南，云南，上海，北京,广东";            string[] str2 = new string[2];            char[] sp = { ',', '.' };            str2 = str1.Split(sp);            for (int i = 0; i < str2.Length; i++)            {                Console.WriteLine(str2[i]);            }            Console.ReadLine();        }    }}

为什么会出现没有分割呢？？？