Issue: Active Directory not showing all users
There is an active directory related issue, which does not list all users available in the AD. This occurs because of the fact that if DirectorySearcher.PageSize is not set then the server defaults that property to 1000.
Set .PageSize property of your searcher object to 1000, sets the page size and LDAP handles the pagination internally automatically. And Michael Freidgeim is a great guy!
Happy roaming around the active directory (0: