Ubuntu :: Error: Device-mapper: Reload Ioctl Failed: Invalid Argument

I'm having some difficulities with truecrypt and cannot figure out what's wrong since this is my first attempt to create hidden encrypted partition. I'm using ubuntu 9.10 64b with latest 6.3a truecrypt. After using truecrypt gui (just command truecrypt) I've tried: create volume-->create volumne within a partition/drive-->hidden trucrypt volume --> select some /dev/sdX by my choice --> select aes & sha512 --> password --> and format it.

when formating finished message "wrong ss, swith or wrong superblock of /dev/loop0" appeared. I've got no idea what could I do with it neither know whats program trying to do! Ok formating's done, then if you're trying to mount that partition then I would expect prompt for password, but that did not happen ...

EDIT: sudo mount /dev/loop0 /media/tmp/ also complaint about wrong superblock, but that does not ring any bell since i've got no idea what /dev/loop0 is or is for...

EDIT2: I've tried another approach also:

sudo truecrypt -t -c
sudo truecrypt -t /dev/sda3 --filesystem=none

but the first command finished creating 100G drive in 1 sec (nonsense) and latter one prints:

Error: device-mapper: reload ioctl failed: Invalid argument
Command failed