新手求教文本数据处理，输出筛选的数据

Question

文本数据格式为

频道号或者节目票号,智能卡号,收藏类型,添加收藏时间,生成时间,节目名称,收藏ID

71630809,700086697570,VOD,2012-02-25 11:43:25,2012-02-25 11:43:25,翻仔和纯纯04（高清）,23059098

71988821,700083392266,VOD,2012-02-26 15:27:56,2012-02-26 15:27:56,海贼王：513蠢蠢欲动的海贼们！惊天动地的新世界,23102901

想选出所有智能卡号一样的记录，输出该条信息。

求教为什么总是显示OutputYMS(string filename, string s1)中 string s1有问题？

代码如下：

using System;  
using System.IO;

using System.Text;
using System.Linq;

namespace 台数据信息查询 
{
    class Program
    {
        private static string[] arr1;
        private static string[] arr2;
    
        
        private static bool IsSameNumber(ref string s1, ref string s2)
        {
            arr1=s1.Split('，');//字符串以逗号分开
            arr2=s2.Split('，');
            s1=arr1[1];
            s2=arr2[1];
            
            if(arr1[1]==arr2[1])
                return true;
            else return false;
        }
        
         
        private static void OutputYMS(string filename, string s1)
        {
            
            Console.WriteLine("{0}\t{1}",filename, string s1);
        }
             
        static void Main(string[] args)  
        {
            string line1,line2;
            int i,S;
            i=S=0;
            StreamReader sr;
            string s1;
            
            
            Console.WriteLine("请输入路径: ");
            string path=Console.ReadLine().ToString();
            Console.WriteLine(); 
            
            DirectoryInfo dirInfo=new DirectoryInfo(path);
            if(dirInfo.Exists)
            {
                
                Console.WriteLine("文件名"+"\t"+"统计记录");
                
                FileInfo[] files=dirInfo.GetFiles();
                foreach(FileInfo file in files)
                {
                    sr=new StreamReader(file.FullName);
                    while((line2=sr.ReadLine())!=null&&(line1=sr.ReadLine())!=null)//一次读两行
                    {
                        if(IsSameNumber(ref line1,ref line2))
                        {
                            i++;
                            s1=Convert.ToString(line1);//转换并相减
                            continue;
                        }
                        else continue;
                    }
                    if(i==0)
                    {
                        Console.WriteLine("没有连续两行一样");
                        break;
                    }
                    else OutputYMS(Path.GetFileNameWithoutExtension(file.FullName), new s1());
                }
            }
            else Console.WriteLine("未找到文件,请检查路径是否正确!");
            
            Console.ReadKey(true);
        }
    }
}