Cannot set write permission for fat partition!

[Sail@]

I know that fat permissions is a common issue here, but I don't think this has been adressed before:
I want to let users that are members of the group "share" (407) be able to read, write and execute files in /ftp-data

/etc/fstab:
...
/dev/hdb1 /ftp-data vfat defaults,uid=nobody,gid=407,umask=707 0 0
...

here is the output i get from ls:
root@pr0nstar:/ftp-data# ls -la
d---rwx--- 12 root share 4.0K Jan 1 1970 .
drwxr-xr-x 22 root root 512 Sep 15 16:10 ..
d---r-x--- 6 root share 4.0K Sep 21 03:30 Incoming
d---r-x--- 31 root share 12K Sep 21 18:39 Music
d---r-x--- 4 root share 4.0K Sep 14 13:04 backup.volvo

No write permission!!! Help!
I've tried adding rw, auto, to fstab also.
I'm stuck!