How can I get tokenGroups from active directory on Windows Server 2003?

Question

I'm trying to load tokenGroups from Active Directory but it isn't working once deployed to a Windows Server (2003). I cannot figure out why, since it works fine locally...

Here is my error:

There is no such object on the server.

And here is my code (the sid variable is the current users SecurityIdentifier pulled from HttpContext):

DirectoryEntry userDE = new DirectoryEntry(string.Format("LDAP://<SID={0}>", sid.Value))
userDE.RefreshCache(new[] { "tokenGroups" });

var tokenGroups = userDE.Properties["tokenGroups"] as CollectionBase;
groups = tokenGroups.Cast<byte[]>()
    .Select(sid => new SecurityIdentifier(sid, 0)).ToArray();

Any ideas why I would get that error?

UPDATE: The error actually happens on the RefreshCache line