WINNT 4 and SP6

Hi
I have a customer that has Winnt 4 on her machine and it has been a collegue of mine to the site to try and update the servicepack on the machine with no success.
When he tries to update the NT4 with the latest SP he gets an error message that says that the update/patch is ment to be used on a WINNT 4 Wrkstn, wich is exactly on what he is trying to install it to.

Has anyone heard of this problem before ?
ANY ideas is a good idea, Thanks !