Native Object - System.Directory Services

[Ganesh Ramamurthy]

Hi Experts,

I am using System.DirectoryServices to authenticate my users who are in the
LDAP. I am using the Active Directory Users in my web application.

I am creating the native object to authenticate the users. I am using the
following code

DirectoryEntry oUserDE = new DirectoryEntry(strPath, strUserID,
strPassword);

try
{
// Bind to the native object to force authentication to happen
Object native = oUserDE.NativeObject;
}
catch (Exception Ex)
{
throw new Exception("User not authenticated.", Ex);
}

However, some of the users are not authenticated with this method.

Object native = oUserDE.NativeObject; // fails for some users
and an exception is thrown.

However, I can authenticate the same user from my windows 2k3 and also from
another old ASP application which uses ADO to query the same LDAP.

Can anyone tell me the reason for such a behaviour and the resolution for
that.

Thanks in advance
Regards
Ganesh