Handling sub-folders Custom Site Map?

I did not upload my code properly sorry..

using System;
using System.IO;
using System.Collections.Generic;
using System.Web;

///

/// Summary description for MyCustomSiteMap
///

public class MyCustomSiteMap : StaticSiteMapProvider
{
    string sourceDir = HttpContext.Current.Server.MapPath(Path.Combine(HttpContext.Current.Request.ApplicationPath, "Content"));

    private SiteMapNode parentNode
    {
        get;
        set;
    }

    private string ExcludedFolders
    {
        get
        {
            return "(App_Data)|(obj)";
        }
    }
    private string ExcludedFiles
    {
        get
        {
            return "";
        }
    }
    public override SiteMapNode BuildSiteMap()
    {
        lock (this)
        {
            parentNode = HttpContext.Current.Cache["SiteMap"] as SiteMapNode;
            if (parentNode == null)
            {
                base.Clear();
                parentNode = new SiteMapNode(this,
                                        sourceDir,
                                        sourceDir + "Default.aspx",
                                        "Home");
                AddNode(parentNode);
                AddFiles(parentNode);
                AddFolders(parentNode);
                HttpContext.Current.Cache.Insert("SiteMap", parentNode);
            }
            return parentNode;
        }
    }
    private void AddFolders(SiteMapNode parentNode)
    {

        List subFolders = new List();
        DirectoryInfo di = new DirectoryInfo(parentNode.Key);
        foreach (DirectoryInfo dir in di.GetDirectories("*", SearchOption.AllDirectories))
        {
            subFolders.Add(dir.Name);
        }
        foreach (var fldrName in subFolders)
        {
            string folderUrl = parentNode.Key + "\\" + fldrName;
            SiteMapNode folderNode = new SiteMapNode(this, folderUrl, null, fldrName);
            AddNode(folderNode, parentNode);
            AddFiles(folderNode);
        }
    }
    private void AddFiles(SiteMapNode folderNode)
    {
        List files = new List();
        DirectoryInfo di = new DirectoryInfo(folderNode.Key);
        foreach (FileInfo file in di.GetFiles("*.pdf"))
        {
            files.Add(file.Name);
        }
        foreach (var fileName in files)
        {
            SiteMapNode fileNode = new SiteMapNode(this,
                                                  folderNode.Key + "/" + fileName,
                                                    null,
                                                fileName);                           
            AddNode(fileNode, folderNode);
            // AddFolders(parentNode);
        }
    }
    protected override SiteMapNode GetRootNodeCore()
    {
        return BuildSiteMap();
    }
}