mount permission

[Luca Ferrari]

HI all,
in my /etc/fstab I've got the following:

//prod/coge     /mnt/prod        smb   users,guest,auto,umask=000      0 0

the problem is that after a computer boot I'm unable to write, as normal user, 
on the /mnt/prod directory, while if I umount and remount it (as a normal 
user) I can do that. What am I missing to allow each normal user to access 
the share in write mode?

Thanks,
Luca