diskless workstations

["nigel barker" <tech@hiroshima-is.ac.jp>]

I'm trying to test diskless workstations by following the Howto on the
wiki. I have got to the part about changing the repositories. I have
changed /etc/apt/sources.list and /opt/ltsp/i386/etc/apt/sources.list as
indicated. I have run apt-get update both inside and outside the chroot,
yet still I get this errot when I try to run /usr/sbin/ltsp-make-client:

error: Unable to use CD/DVD as source for converting the ltsp chroot
error: to a diskless workstation.
error: The reason is that the CD/DVD is not a signed APT repository.
error: Edit /opt/ltsp/i386/etc/apt/sources.list to fix this.

I can't see where I've gone wrong. The CD is commented out in both
sources.list

I am using RC4 DVD install.

thanks!

nigel