mounting usbstick in fc2

Hi,
I am trying to mount my usbstick. But it won't happen.
Hardware browser detects the usbstick (/dev/sda). I created a new directory in /mnt (mkdir usb). I added a line in /fstab

]$ cat /etc/fstab
LABEL=/ / ext3 defaults 1 1
none /dev/pts devpts gid=5,mode=620 0 0
none /dev/shm tmpfs defaults 0 0
none /proc proc defaults 0 0
none /sys sysfs defaults 0 0
/dev/hda3 swap swap defaults 0 0
/dev/cdrom /mnt/cdrom udf,iso9660 noauto,owner,kudzu,ro 0 0
/dev/fd0 /mnt/floppy auto noauto,owner,kudzu 0 0
/dev/sda /mnt/usb vfat noauto,owner,user,sync 0 0

But whwn I try to mount the system coms up with this message:

]# mount -t vfat /dev/sda /mnt/usb
mount: wrong fs type, bad option, bad superblock on /dev/sda,
      or too many mounted file systems

When I change files type (in /fstab) in "auto", the following lines occur:

# mount /dev/sda /mnt/usb
mount: you must specify the filesystem type

Can someone give me a hint?
Thanks,
Peter.