Empty hash? "Disk error"

[Trolltramp]

Thanks! For some reason the option to encrypt whole disk was in grey (I couldn't choose it), so I've encrypted whole partition instead (the only one). In disk's properties it's name was /dev/sda1 so that's the name I've used. Now hash file looks ok I guess. Also the 1st 512 bytes of whole disk don't show error message now.
2nd thing, I'm absolutely sure that I haven't created hidden volume and that on startup of this disk I see VeraCrypt boot loader (but probably the only partition encryption works like whole disk encryption, so that's the reason).
I'll post later final results