how to sort the values of listbox

Question

i want to sort the values of listbox, both in ascending and descending order
but in the following code there is some error... pls help
using System;
using System.Collections;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace WindowsFormsApplication5
{
    public partial class Form1 : Form
    {
        ArrayList list1 = new ArrayList();
        public Form1()
        {
            InitializeComponent();

        }         
        private void button1_Click(object sender, EventArgs e)
        {
            listBox1.Items.Add(textBox1.Text);
            list1.add(textBox1.Text);
            textBox1.Clear();
        }

        private void button2_Click(object sender, EventArgs e)
        {
            list1.Sort();
            Object[] arr = list1.ToArray();
            listBox2.Items.Clear();
            listBox2.Items.AddRange(arr);

            list1.Reverse();
            Object[] arr1 = list1.ToArray();
            listBox3.Items.Clear();
            listBox3.Items.AddRange(arr1);
        }