มัน error ว่า Object reference not set to an instance of an object. อ่ะครับ

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Diagnostics;
using System.Text;
using System.Windows.Forms;
using System.Net;
using System.IO;
using WIA;

namespace BlogWebcam
{
    public partial class Main : Form
    {
        private int currentFileNumber = 0;
        private string currentFileName = String.Empty;
        private bool tooManyFiles = false;
        private Device device = null;
        private string jpegGuid = string.Empty;
        BlogWebcam.Properties.Settings settings = BlogWebcam.Properties.Settings.Default;

        public Main()
        {
            InitializeComponent();
        }

        private void btnStart_Click(object sender, EventArgs e)
        {
            SaveSettings();
            if (btnStart.Text == "Start")
            {
                DeviceManager manager = new DeviceManagerClass();
                foreach (DeviceInfo info in manager.DeviceInfos)
                {
                    if (info.DeviceID == settings.DeviceID)
                    {
                        device = info.Connect();
                        break;
                    }

                }

                timerWebcam.Enabled = true;
                btnStart.Text = "Stop";
            }
            else
            {
                timerWebcam.Enabled = false;
                device = null;
                btnStart.Text = "Start";
            }
        }


        private string GetFreeFileName()
        {
            while (true)
            {
                currentFileName = currentFileNumber.ToString() + ".jpg";
                if (tooManyFiles == true)
                {
                    System.IO.File.Delete(currentFileName);
                }
                if (System.IO.File.Exists(currentFileName) == false)
                {
                    return currentFileName;
                }
                currentFileNumber++;

                if (currentFileNumber > 50)
                {
                    currentFileNumber = 0;
                    tooManyFiles = true;
                }
            }
        }

        public void SaveSettings()
        {
            settings.TimeInMinutes = Convert.ToInt32(numTimer.Value);
            timerWebcam.Interval = settings.TimeInMinutes * 60000;
            settings.FTPServerURL = txtFTPURL.Text;
            settings.Save();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            Microsoft.Win32.RegistryKey jpegKey = Microsoft.Win32.Registry.ClassesRoot.OpenSubKey (@"CLSID\{D2923B86-15F1-46FF-A19A-DE825F919576}\SupportedExtension\.jpg");
            jpegGuid = jpegKey.GetValue("FormatGUID") as string;     <<<< error ตรงนี้อ่ะครับ 

            //reasonable default
            if (settings.TimeInMinutes <= 0)
            {
                settings.TimeInMinutes = 15;
            }

            timerWebcam.Interval = settings.TimeInMinutes * 60000;
            numTimer.Value = settings.TimeInMinutes;
            txtFTPURL.Text = settings.FTPServerURL;
        }

        private void btnConfigure_Click(object sender, EventArgs e)
        {
            CommonDialogClass class1 = new CommonDialogClass();
            Device d = class1.ShowSelectDevice(WiaDeviceType.UnspecifiedDeviceType, true,false);
            if (d != null)
            {
                settings.DeviceID = d.DeviceID;
                settings.Save();
            }
        }

        private void timerWebcam_Tick(object sender, EventArgs e)
        {
            timerWebcam.Enabled = false;
            string filename = TakePicture();
            if (string.IsNullOrEmpty(filename) == false)
            {
                FTPUploadFile(filename);
            }
            timerWebcam.Enabled = true;
        }

        private void FTPUploadFile(string filename)
        {
            try
            {
                FtpWebRequest request = (FtpWebRequest)WebRequest.Create(settings.FTPServerURL);
                request.Method = WebRequestMethods.Ftp.UploadFile;
                request.UseBinary = true;
                FileInfo fileInfo = new FileInfo(filename);
                byte[] fileContents = new byte[fileInfo.Length];
                
                using (FileStream fr = fileInfo.OpenRead())
                {
                    fr.Read(fileContents, 0, Convert.ToInt32(fileInfo.Length));
                }

                using (Stream writer = request.GetRequestStream())
                {
                    writer.Write(fileContents, 0, fileContents.Length);
                }
                
                using (FtpWebResponse response = (FtpWebResponse)request.GetResponse())
                {

                }	
            }
            catch (WebException)
            {
                throw;
            }
        }

        private string TakePicture()
        {
            string filename = String.Empty;
            if (device != null)
            {
                Item item = device.ExecuteCommand(CommandID.wiaCommandTakePicture);
                foreach (string format in item.Formats)
                {
                    if (format == jpegGuid)
                    {
                        WIA.ImageFile imagefile = item.Transfer(format) as WIA.ImageFile;
                        filename = GetFreeFileName();
                        if (string.IsNullOrEmpty(filename) == false)
                        {
                            imagefile.SaveFile(filename);
                        }
                        this.picLastImage.Load(filename);
                        return filename;
                    }
                }
            }
            else
            {
                btnConfigure_Click(null, null);
            }
            return filename;
        }

        private void Main_FormClosing(object sender, FormClosingEventArgs e)
        {
            timerWebcam.Enabled = false;
            SaveSettings();
        }

        private void notifyIcon1_Click(object sender, EventArgs e)
        {
            this.WindowState = FormWindowState.Normal;
            this.Show();
        }
    }
}