Read from a XML file to an Array node by node in C#

The XML file is like this,There are about 20 Nodes(modules) like this.

<list>
<module code="ECSE502">
<code>ECSE502</code>
<name>Algorithms and Data structures</name>
<semester>1</semester>
<prerequisites>none</prerequisites>
<lslot>0</lslot>
<tslot>1</tslot>
<description>all about algorythms and data structers with totorials and inclass tests</description>
</module>    
</list>

I did the following code. But when I debugged it it even didn't went inside to foreach function.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Xml;

namespace ModuleEnrolmentCW
{
    class XMLRead
    {

        public string[] writeToXML(string s)
        {
            string text = s;           
            string[] arr = new string[6];

            XmlDocument xml = new XmlDocument();
            xml.Load("modules.xml");

            XmlNodeList xnList = xml.SelectNodes("list/module[@code='" + text + "']");
            foreach (XmlNode xn in xnList)
            {
                arr[0] = xn.SelectSingleNode("code").InnerText;
                arr[1] = xn.SelectSingleNode("name").InnerText;
                arr[2] = xn.SelectSingleNode("semester").InnerText;
                arr[3] = xn.SelectSingleNode("prerequisites").InnerText;
                arr[4] = xn.SelectSingleNode("lslot").InnerText;
                arr[5] = xn.SelectSingleNode("tslot").InnerText;                            
            }

            return arr;
        }


    }
}

Please tell me where is the wrong??

Here is the rest of the code

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;

namespace ModuleEnrolmentCW
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        string selected;
        private void listBox1_SelectedIndexChanged(object sender, EventArgs e)
        {
            XMLRead x = new XMLRead();
            selected = (string)listBox1.SelectedItem;
            string[] arr2 = x.writeToXML(selected);

            label11.Text = arr2[0];

        }
    }
}