Xml file issue

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.Speech.Synthesis;
using System.Xml;

namespace MyIEAddon1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button3_Click(object sender, EventArgs e)
        {
            SpeechSynthesizer audio = new SpeechSynthesizer();// repeat what i say in computer speech
            if (textBox1.Text == "" | textBox1.Text == " " | textBox1.Text == "  " | textBox1.Text == null)
            {
                MessageBox.Show("No word entered, Please enter your word ", "Error Message");
            }

            else
            {// (!string.IsNullOrEmpty(textBox1.Text))   // (listBox1.Items.Contains(textBox1.Text))

                if (!string.IsNullOrEmpty(textBox1.Text) && listBox1.Items.OfType<string>().Select(p => p.ToUpper()).Contains(textBox1.Text.ToUpper()))  // 
                {
                    MessageBox.Show("Sorry, Word that you try to add is already on the XML file", "Error Message");
                    textBox1.Text = " ";
                }

                else
                {
                    listBox1.Items.Add(textBox1.Text);
                }
                textBox1.Text = "";

            }
        }

        private void button5_Click(object sender, EventArgs e)
        {
            button4.Enabled = true; // disable save xml file
            button5.Enabled = false; //  enable load grammar to load grammar from xml file
            button3.Enabled = true; //  disable add button  

            XmlTextReader reader = new XmlTextReader("Grammar.xml");
            XmlNodeType type;

            while (reader.Read())
            {
                type = reader.NodeType;

                if (type == XmlNodeType.Element)
                {

                    if (reader.Name == "item")
                    {
                        reader.Read();

                        listBox1.Items.Add(reader.Value);
                    }
                }
            }

            reader.Close();
        }

        private void button4_Click(object sender, EventArgs e)
        {
            button5.Enabled = false; // disable load xml file
            button4.Enabled = true;  // enable save xml file

            try
            {
                XmlTextWriter writer = new XmlTextWriter("Grammar.xml", Encoding.UTF8);
                writer.Formatting = Formatting.Indented;

                writer.WriteStartDocument();
                writer.WriteStartElement("grammar");
                writer.WriteAttributeString("xmlns", "http://www.w3.org/2001/06/grammar");
                writer.WriteAttributeString("xmlns:xsi", "http://www.w3.org/2001/XMLSchema-instance");
                writer.WriteAttributeString("xml:lang", "en-US");
                writer.WriteAttributeString("version", "1.0");
                writer.WriteAttributeString("root", "command1");
                writer.WriteStartElement("rule ");
                writer.WriteAttributeString("id", "command1");
                writer.WriteAttributeString("scope", "public");
                writer.WriteStartElement("one-of");


                foreach (string item in listBox1.Items)
                {
                    writer.WriteStartElement("item");
                    writer.WriteString(item);
                    writer.WriteEndElement(); //WORD
                }

                writer.WriteEndElement(); //COMMAND
                writer.WriteEndElement();
                writer.WriteEndElement();
                writer.WriteEndDocument();// End Document

                writer.Close();
                MessageBox.Show("THE NEW WORDS ADD TO THE XML FILE !!", "Message");
            }
            catch
            { MessageBox.Show("InvalidCastException"); }

            int num = listBox1.Items.Count;  //  to count tne number of words will do the folowing :
            string m;
            m = Convert.ToString(num);

            foreach (string item in listBox1.Items)

                label4.Text = m;
        }
    }
}

<?xml version="1.0" encoding="utf-8"?>
<grammar xmlns="http://www.w3.org/2001/06/grammar" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xml:lang="en-US" version="1.0" root="command1">
  <one-of>
    <item>it322</item>
    <item>it419</item>
    <item>it211</item>
    <item>it327</item>
    <item>itnetwork2</item>
    <item>it212</item>
    <item>itnetwork1</item>
    <item>it321</item>
    <item>it323</item>
    <item>331it</item>
    <item>itttttt</item>
    <item>1111</item>
  </one-of>
</grammar>