still doesn't work, after it connects to the various services in the sources list and downloads a bunch of packages, I get this error message.

W: GPG error: http://ftp.de.debian.org unstable Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 010908312D230C5F
W: GPG error: http://ftp.de.debian.org testing Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 010908312D230C5F
W: You may want to run apt-get update to correct these problems

But thanks for helping.