error information in log file

using System;
using System.Collections.Generic;
using System.Text;
using System.IO;
using System.Configuration;
namespace GTSS
{
    public class Logger
    {
        public string logFile = "";
        public string dataLogFile = "";
        public Logger()
        {
            System.Configuration.AppSettingsReader reader1 = new System.Configuration.AppSettingsReader();
            logFile = (string)reader1.GetValue("LogFile", logFile.GetType());
            dataLogFile = (string)reader1.GetValue("DataLogFile", dataLogFile.GetType());
        }
        public void AddLogEntry(string entry)
        {
            StreamWriter outFile = new StreamWriter(logFile, true);
            //StreamWriter outfile = new StreamWriter(logFile);
            //s.Append(quotes + "LVTS" + quotes + "," + quotes + dtTrades.Rows.Count.ToString() + quotes + "," + quotes + DateTime.Now.ToString("MM/dd/yyyy HH:mm:ss") + quotes + "," + quotes + DateTime.Now.ToString("MM/dd/yyyy") + quotes);
            outFile.WriteLine(entry);
            outFile.Close();
        }
        public void archive_log()
        {
            if (File.Exists(logFile.ToString()))
            {
                File.Copy(logFile, logFile.Substring(0, logFile.Length - 4) + "_" +
                                                                            DateTime.Now.Year.ToString() +
                                                                            DateTime.Now.Month.ToString() +
                                                                            DateTime.Now.Day.ToString() + "_" +
                                                                            DateTime.Now.Hour.ToString() +
                                                                            DateTime.Now.Minute.ToString() + ".txt");
                File.Delete(logFile.ToString());
            }
        }
        public void AddDataLogEntry(string entry)
        {
            StreamWriter outFile = new StreamWriter(dataLogFile, true);
            //StreamWriter outfile = new StreamWriter(logFile);
            //s.Append(quotes + "LVTS" + quotes + "," + quotes + dtTrades.Rows.Count.ToString() + quotes + "," + quotes + DateTime.Now.ToString("MM/dd/yyyy HH:mm:ss") + quotes + "," + quotes + DateTime.Now.ToString("MM/dd/yyyy") + quotes);
            outFile.WriteLine(entry);
            outFile.Close();
        }
        public void delete_data_log()
        {
            if (File.Exists(dataLogFile.ToString()))
            {
                File.Delete(dataLogFile.ToString());
            }
        }
    }
}