Windows Impersonation failed

I am using following code to implement impersonation for the particular windows account,which is failing.Please help.

using System.Security.Principal;
using System.Runtime.InteropServices;

public partial class Source_AddNewProduct : System.Web.UI.Page
{
[DllImport("advapi32.dll", SetLastError = true)]
    static extern bool LogonUser(
        string principal,
        string authority,
        string password,
        LogonSessionType logonType,
        LogonProvider logonProvider,
        out IntPtr token);
    [DllImport("kernel32.dll", SetLastError = true)]
    static extern bool CloseHandle(IntPtr handle);

    enum LogonSessionType : uint
    {
        Interactive = 2,
        Network,
        Batch,
        Service,
        NetworkCleartext = 8,
        NewCredentials
    }
    enum LogonProvider : uint
    {
        Default = 0, // default for platform (use this!)
        WinNT35,     // sends smoke signals to authority
        WinNT40,开发者_开发问答     // uses NTLM
        WinNT50      // negotiates Kerb or NTLM
    }
//impersonation is used when user tries to upload an image to a network drive
protected void btnPrimaryPicUpload_Click1(object sender, EventArgs e)
    {
        try
        {
            string mDocumentExt = string.Empty;
            string mDocumentName = string.Empty;
            HttpPostedFile mUserPostedFile = null;
            HttpFileCollection mUploadedFiles = null;
            string xmlPath = string.Empty;

            FileStream fs = null;
            StreamReader file;
            string modify;

            mUploadedFiles = HttpContext.Current.Request.Files;

            mUserPostedFile = mUploadedFiles[0];

            if (mUserPostedFile.ContentLength >= 0 && Path.GetFileName(mUserPostedFile.FileName) != "")
            {

                mDocumentName = Path.GetFileName(mUserPostedFile.FileName);
                mDocumentExt = Path.GetExtension(mDocumentName);
                mDocumentExt = mDocumentExt.ToLower();
                if (mDocumentExt != ".jpg" && mDocumentExt != ".JPG" && mDocumentExt != ".gif" && mDocumentExt != ".GIF" && mDocumentExt != ".jpeg" && mDocumentExt != ".JPEG" && mDocumentExt != ".tiff" && mDocumentExt != ".TIFF" && mDocumentExt != ".png" && mDocumentExt != ".PNG" && mDocumentExt != ".raw" && mDocumentExt != ".RAW" && mDocumentExt != ".bmp" && mDocumentExt != ".BMP" && mDocumentExt != ".TIF" && mDocumentExt != ".tif")
                {
                    Page.RegisterStartupScript("select", "<script language=" + Convert.ToChar(34) +
                        "VBScript" + Convert.ToChar(34) + "> MsgBox " + Convert.ToChar(34) + "Please upload valid picture file format" + Convert.ToChar(34) +
                        " , " + Convert.ToChar(34) + "64" + Convert.ToChar(34) + " , " + Convert.ToChar(34) + "WFISware" + Convert.ToChar(34) + "</script>");

                }
                else
                {
                    int intDocLen = mUserPostedFile.ContentLength;
                    byte[] imageBytes = new byte[intDocLen];
                    mUserPostedFile.InputStream.Read(imageBytes, 0, mUserPostedFile.ContentLength);
                    //xmlPath = @ConfigurationManager.AppSettings["ImagePath"].ToString();
                    xmlPath = Server.MapPath("./../ProductImages/");
                    mDocumentName = Guid.NewGuid().ToString().Replace("-", "") + System.IO.Path.GetExtension(mUserPostedFile.FileName);

                    //if (System.IO.Path.GetExtension(mUserPostedFile.FileName) == ".jpg")
                    //{

                    //}
                    //if (System.IO.Path.GetExtension(mUserPostedFile.FileName) == ".gif")
                    //{

                    //}

                    mUserPostedFile.SaveAs(xmlPath + mDocumentName);

                    //Remove commenting till upto stmt xmlPath = "./../ProductImages/"; to implement impersonation
                    byte[] bytContent;
                    IntPtr token = IntPtr.Zero;
                    WindowsImpersonationContext impersonatedUser = null;

                    try
                    {
                        // Note: Credentials should be encrypted in configuration file
                        bool result = LogonUser(ConfigurationManager.AppSettings["ServiceAccount"].ToString(), "ad-ent",
                                                ConfigurationManager.AppSettings["ServiceAccountPassword"].ToString(),
                                                LogonSessionType.Network,
                                                LogonProvider.Default,
                                                out token);
                        if (result)
                        {
                            WindowsIdentity id = new WindowsIdentity(token);

                            // Begin impersonation
                            impersonatedUser = id.Impersonate();
                            mUserPostedFile.SaveAs(xmlPath + mDocumentName);

                        }
                        else
                        {
                            throw new Exception("Identity impersonation has failed.");
                        }
                    }
                    catch
                    {
                        throw;
                    }
                    finally
                    {
                        // Stop impersonation and revert to the process identity
                        if (impersonatedUser != null)
                            impersonatedUser.Undo();
                        // Free the token
                        if (token != IntPtr.Zero)
                            CloseHandle(token);
                    }


                    xmlPath = "./../ProductImages/";
                    xmlPath = xmlPath + mDocumentName;
                    string o_image = xmlPath;  //For impersoantion uncomment this line and comment next line
                    //string o_image = "../ProductImages/" + mDocumentName;

                    ViewState["masterImage"] = o_image;
                    //fs = new FileStream(xmlPath, FileMode.Open, FileAccess.Read);
                    //file = new StreamReader(fs, Encoding.UTF8);
                    //modify = file.ReadToEnd();
                    //file.Close();

                    //commented by saurabh kumar 28may'09
                    imgImage.Visible = true;
                    imgImage.ImageUrl = ViewState["masterImage"].ToString();
                    img_Label1.Visible = false;
                }


                //e.Values["TemplateContent"] = modify;
                //e.Values["TemplateName"] = mDocumentName.Replace(".xml", "");
            }

        }
        catch (Exception ex)
        {
            ExceptionUtil.UI(ex);
            Response.Redirect("errorpage.aspx");
        }


    }
}

The code on execution throws system.invalidoperation exception.I have provided full control to destination folder to the windows service account that i am impersonating.

I cannot understand what you are trying. But what I can say is that you can impersonate any user successfully only if the account the application is running is an administrator. In case the account in which the app is running is a non-admin use runas. Incase you are using ASP.NET, make sure that the website is running under an impersonated Admin account who has admin rights for that network share.