passfifo not working in 10.04

[DW]

Binary package hint: cryptsetup

Hello,
I've recently changed from 9.10 to 10.04 and I'm using root encryption. Everything is working fine except for the possibility of remote unlocking over dropbear ssh in initramfs. in 9.10 it worked fine but 10.04 echo -n "Passphrase" > /lib/cryptsetup/passfifo doesn't seem to work anymore (yeah I enter the correct passphrase I tipplechecked :).
I would expect it to continue with booting but instead nothing happens.

I would like to continue using the remote unlock feature so any help is appreciated:)

Greetings
DW

apt-cache policy cryptsetup
cryptsetup:
  Installed: 2:1.1.0~rc2-1ubuntu13
  Candidate: 2:1.1.0~rc2-1ubuntu13
  Version table:
 *** 2:1.1.0~rc2-1ubuntu13 0
        500 http://de.archive.ubuntu.com/ubuntu/ lucid/main Packages
        100 /var/lib/dpkg/status

lsb_release -rd
Description: Ubuntu 10.04 LTS
Release: 10.04