mount_msdos: /dev/fd0a on /mnt: Device not configured

[Alexander_(_dot_)_Farber_(_at_)_t-online_(_dot_)_de (Alexander Farber)]

Hi,

why do I get this error:

alex# mount -t msdos /dev/fd0a /mnt
mount_msdos: /dev/fd0a on /mnt: Device not configured

I have read "man fd", "man mount" and "man mount_msdos" 
and searched the FAQ but don't see the reason. Do I have 
to enable something in kernel? I have also tried:

alex# disklabel fd0
disklabel: /dev/rfd0c: Device not configured

alex# mount -t msdos /dev/fd0 /mnt
mount_msdos: /dev/fd0 on /mnt: No such file or directory

alex# mount -t msdos /dev/fd0c /mnt
mount_msdos: /dev/fd0c on /mnt: Device not configured

TIA
Alex