smart media changing problem

I have a Camedia USB smart media reader which Null recognizes and allows
me to mount as /mnt/smedia with an fstab entry as follows.

/dev/sda1       /mnt/smedia     vfat    noauto,user 0 0

If I have a smart media card in the reader at boot, I can manually
mount/unmount it just fine and read the data on the card.

[gerry@gstpc gerry]$ mount /mnt/smedia
mount: block device /dev/sda1 is write-protected, mounting read-only
[gerry@gstpc gerry]$ umount /mnt/smedia

However, if I want to remove the card after unmounting the device and
insert another card and mount the device, I get the following error;

[gerry@gstpc gerry]$ mount /mnt/smedia
mount: block device /dev/sda1 is write-protected, mounting read-only
mount: wrong fs type, bad option, bad superblock on /dev/sda1,
       or too many mounted file systems

There must be some way to use multiple smart media cards without
rebooting.  Any suggestions?  Thanks.

gerry