Windows 2003 domain. Problems delegating UnlockTime to one user from a group

Question

I've created a Local Group with UnlockTime (read and write) privileges. I tested with a new user account and works well.

I added a real domain user to that group and he can't unlock accounts. Looking for diferences on configuration I only notice that the real user have a tab "Delegation" on the User Manager for Active Directory.

Any idea?

Thanks