how to add user in active directory group

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C#

C#4.0

SharePoint

service

Hi,

i am try to add user to activedirectory group in windows server.that users call from share point list.i am get the items from share point list successfully.but i am trying to add users to active directory distribution group.some exception and errors came.so please help me to find the solution

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
//SharePoint namespace
using Microsoft.SharePoint.Client;
using System.Net;
using EnCryptDecrypt;
using System.Configuration;
using System.Security.Cryptography;
using System.IO;
using System.DirectoryServices;
using System.DirectoryServices.AccountManagement;

namespace ConsoleApplication4
{
    class Program
    {
        static void Main(string[] args)
        {
            string key = "a text phrase";
            string abc = ConfigurationSettings.AppSettings[0];
            string cmc = ConfigurationSettings.AppSettings[1];
            // string cmc = "HjMoHs9EMx2NDTdkv4QDUg==";

            // string abc = "s1SYwK14I+PvRZBZtWdDw==";
            ClientContext clientContext = new ClientContext("http://xxxxxxxx");
            NetworkCredential cred = new NetworkCredential();
            //string encrypt = encrypt(abc, key);
            cred.UserName = abc;

            string decryptedText = CryptorEngine.Decrypt(cmc, key);

            cred.Password = decryptedText;
            clientContext.Credentials = cred;
            List list = clientContext.Web.Lists.GetByTitle("account");
            CamlQuery camlQuery = new CamlQuery();
            camlQuery.ViewXml = "<View/>";
            ListItemCollection listItems = list.GetItems(camlQuery);
            clientContext.Load(list); clientContext.Load(listItems);
            clientContext.ExecuteQuery();
            foreach (ListItem listItem in listItems)
                Console.WriteLine("\nTitle: {0}", listItem["Title"]);
          
            DirectoryEntry directoryEntry;
            try
            {
                directoryEntry = new DirectoryEntry("LDAP://CN=IT,CN=Users, DC=dev, DC=com");
                directoryEntry.RefreshCache();
                DirectoryEntry groupContact = new DirectoryEntry("LDAP://CN=,CN=Users, DC=dev, DC=com");
                directoryEntry.Properties["member"].Add(groupContact.Properties);
                directoryEntry.CommitChanges();
            }
            catch (Exception e)
            {
                 var msg = e.Message.ToString();
                throw;
            }
            Console.ReadLine();
        }

       
    }
    
}