losetup oddity

[PaulBx1]

I was wanting to e2fsck my pupsave, so I booted "pfix=ram" and ran losetup first since my pupsave is encrypted. It asked for my encryption password, which it accepted, but then I kept getting this result:

ioctl: LOOP_SET_STATUS: Invalid argument

However, when I booted using another pupsave, and ran the identical command, it worked properly.

The command I was running was:
losetup-FULL -e aes /dev/loop6 pup_save_crypta216.2fs

Just to be sure, I looked for losetup-FULL to be sure I didn't have a different version. I found only what I expected:
/initrd/pup_ro2/bin/losetup-FULL
/bin/losetup-FULL

It's not a big deal because I just used that other pupsave to get the job done, but I'm just wondering why losetup failed booting into ram. Anyone have an idea?

I'm running 2.16, but I tried this booting into ram with a Puppy 4.1 alpha and got the same result.