some group perms not copied with XCOPY

Over the weekend we used XCOPY to copy our NT4.0 server folder structure to a new 2k file server but some of the groups now can’t access some of the subfolders. Its they the subfolders are not shared for them to use. We have users with a group called Managers who have permissions to access one of these subfolders. They show with those perms on the server but if I try to add them again that group does not show in the list of groups/users selectable from the 2k server.