Error with Directory.Services when on production

The following code works fine in Visual Studio Development enviroment on my local machine. However when I move the files to a Windows 2008 R2 IIS 7.5 machine I get the following error:

[DirectoryServicesCOMException (0x80072020): An operations error occurred. ] _Default.GetFullName(String strLoginName, String& STR_FIRST_NAME, String& STR_LAST_NAME, String& STR_DISPLAY_NAME, String& STR_MAIL, String& STR_OFFICE_PHONE, String& STR_ADDRESS) in c:\AuthTest\Default.aspx.cs:87 _Default.Page_Load(Object sender, EventArgs e) in c:\AuthTest\Default.aspx.cs:23
System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e) +25 System.Web.UI.Control.LoadRecursive() +71 System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +3064

I have Windows Authentication enabled on IIS so I'm not sure if I'm missing something else. Both my local machine and the web server are in the same domain.

Here is my code:

using System;
using System.DirectoryServices;
using System.Web.Hosting;

public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        //Gets the extracted User Name using a method.
        string strUserID = ExtractUserName(User.Identity.Name.ToString());

        string STR_FIRST_NAME;
        string STR_LAST_NAME;
        string STR_DISPLAY_NAME;
        string STR_MAIL;
        string STR_OFFICE_PHONE;
        string STR_ADDRESS;


        GetFullName(strUserID, out STR_FIRST_NAME, out STR_LAST_NAME, out STR_DISPLAY_NAME, 
            out STR_MAIL, out STR_OFFICE_PHONE, out STR_ADDRESS);

        lblHello.Text = "Your User ID is: " + strUserID;
        TextBox1.Text = 
            "Your name is: " + STR_FIRST_NAME + " " + STR_LAST_NAME + Environment.NewLine +
            "Display Name: " + STR_DISPLAY_NAME + Environment.NewLine + 
            "Email address: " + STR_MAIL + Environment.NewLine +
            "Office Phone: " + STR_OFFICE_PHONE + Environment.NewLine +
            "Address: " + STR_ADDRESS;
    }

        //Retrives User Name from DomainName\\UserName 
        private static string ExtractUserName(string path) 
        { 
            string[] userPath = path.Split(new char[] { '\\' }); 
            return userPath[userPath.Length - 1]; 
        }

        public static string GetFullName(string strLoginName, 
            out string STR_FIRST_NAME, 
            out string STR_LAST_NAME, 
            out string STR_DISPLAY_NAME, 
            out string STR_MAIL, 
            out string STR_OFFICE_PHONE, 
            out string STR_ADDRESS)
        {
            string userName = ExtractUserName(strLoginName);

            SearchResult result = null;

            using (HostingEnvironment.Impersonate())
            {
                DirectorySearcher search = new DirectorySearcher();
                search.Filter = String.Format("(SAMAccountName={0})", userName);
                search.PropertiesToLoad.Add("cn");
                STR_FIRST_NAME = "";
                STR_LAST_NAME = "";
                STR_DISPLAY_NAME = "";
                STR_MAIL = "";
                STR_OFFICE_PHONE = "";
                STR_ADDRESS = "";

                try
                {
                    result = search.FindOne();

                    foreach (System.Collections.DictionaryEntry direntry in result.Properties)
                    {
                        STR_FIRST_NAME = result.GetDirectoryEntry().Properties["givenName"].Value.ToString();
                        STR_LAST_NAME = result.GetDirectoryEntry().Properties["SN"].Value.ToString();
                        STR_DISPLAY_NAME = result.GetDirectoryEntry().Properties["DisplayName"].Value.ToString();
                        STR_MAIL = result.GetDirectoryEntry().Properties["mail"].Value.ToString();
                        STR_OFFICE_PHONE = result.GetDirectoryEntry().Properties["telephoneNumber"].Value.ToString();
                        STR_ADDRESS = result.GetDirectoryEntry().Properties["streetAddress"].Value.ToString();
                    }
                    return null;
                }
                catch (Exception ex)
                {
                    throw ex;
                }

            }
        }
}

Again everything works fine on my local machine in the VS Testing enviroment. I'm probably missing some kind of configuration in IIS?

Thanks in Advance.

First thing would be to check that the IIS application pool identity has the correct permissions to AD.

Also as a side note here is something to read regarding your catch { throw ex}

http://www.tkachenko.com/blog/archives/000352.html