C# - RichTextBox - Won't Work

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.IO;

namespace McMayhem.GUI
{
    public partial class TextFiles : Form
    {
        public TextFiles()
        {
            InitializeComponent();
        }


        private void txtRules_TextChanged(object sender, EventArgs e)
        {
        if (File.Exists("Rules.txt"))
            {
                txtRules.Text = "Rules for " + Server.Version + ":";
                foreach (string line in File.ReadAllLines(("Rules.txt")))
                {
                    txtRules.AppendText("\r\n           " + line);
                }
            }
        }
        }
        }