Root isn't God

[Nicolò Nepote <nepote cclinf polito it>]

I have mounted a fat32 partition 7dev/hda2 on /mnt/data with the vfat option
and added an entry in /etc/fstab with auto option. The folder /mnt/data was
created with default umask and has 755 permissions. In order to have the
possibility to write on that disk when I login as "nepote" (that is my usual
identity and is part of the group "root") i logged in as root and:

chmod 775 /mnt/data -R

the command returns a list off "you don't have enough permissions (requested
775, was 755)"

?????????