Hi,

I am currently working as MOSS developer.

Now am developing a intranet site,in that i developing business functionality as application pages. In home page(sharepoint site collection) custom webpart i am tracking employee supervisor in active directory account by using LDAP path(system.directoryservice namespace),but when i am put webpart(deployed in GAC) into home page i got error "The authentication mechanism is unknown.

"
EXCEPTION DETAILS

System.Runtime.InteropServices.COMException: The authentication mechanism is unknown.

CODING

using System;
using System.Collections.Generic;
using System.Text;
using System.Data;
using System.DirectoryServices;
using Microsoft.SharePoint;
using Microsoft.SharePoint.Administration;

namespace RetSuperVisor
{
    public class ReturnUser
    {

        public string GetProperty(SearchResult searchResult, string PropertyName)
        {
            if (searchResult.Properties.Contains(PropertyName))
            {
                return searchResult.Properties[PropertyName][0].ToString();
            }
            else
            {
                return string.Empty;
            }
        }

        public string ValidateUser(string username)
        {
            DirectoryEntry de = new DirectoryEntry("LDAP://MYDOMAIN", "username", "pwd",AuthenticationTypes.Secure);

            DirectorySearcher deSearch = new DirectorySearcher();
            deSearch.SearchRoot = de;

            deSearch.Filter = "(&(objectClass=user)(SAMAccountName=" + username + "))";
            deSearch.SearchScope = SearchScope.Subtree;
            string[] arUser = new string[100];
            foreach (SearchResult results in deSearch.FindAll())
            {
                arUser[0] = GetProperty(results, "manager");

            }
            string user = "";
            int chk = 0;
            int chk1 = 0;
            for (int i = 0; i < arUser[0].Length; i++)
            {
                if (arUser[0].Substring(i, 1).ToString() == @"=")
                {
                    chk = 1;
                }

                if (chk == 1 && chk1 == 0 && arUser[0].Substring(i, 1).ToString() != @"=")
                {
                    if (arUser[0].Substring(i, 1).ToString() != @",")
                    {
                        user = user + arUser[0].Substring(i, 1).ToString();
                    }
                    else
                    {
                        chk1 = 1;
                        break;
                    }

                }
            }

            deSearch.Filter = "(&(objectClass=user)(cn=" + user + "))";
            deSearch.SearchScope = SearchScope.Subtree;

            string[] arSupUser = new string[100];
            string supuser= "";
            foreach (SearchResult results1 in deSearch.FindAll())
            {

                arSupUser[0] = GetProperty(results1, "userPrincipalName");

            }

            for (int i = 0; i < arSupUser[0].Length; i++)
            {
                if (arSupUser[0].Substring(i, 1).ToString() != @"@")
                {
                    supuser = supuser + arSupUser[0].Substring(i, 1).ToString();
                }
                else
                {
                    break;
                }

            }
            return supuser;


        }
    }
}


anyone can help in this?