GRUB error on encrypted sdcard

[Heptas Torres <heptator@gmail.com>]

Hello
I want to set up wheezy on an encrypted sdcard, which I intend to
boot/use on different machines. I need an OS on an sdcard, i.e.
potable, supporting FDE.
I have installed pretty much the default system with LVM and
encryption on an sdcard. I booted first time on a machine and it
worked. Then I booted on another one and did not work. GRUB gives
"error: file not found" and goes into rescue mode. Then I tried to
switch to the original one which initially worked, but this time
didn't - same error (GRUB file not found). Has anyone faced similar
problem and has any ideas what could go wrong?
thank you
- heptas