Comment 243 for bug 1493888

I've been installing from the main repositories, but had previously tried using the wily-proposed instances without success. However, I've tried again, using the following steps (based on reply #123):
1) Checked /etc/apt/sources.list, and it already includes the line "deb http://gb.archive.com/ubuntu wily-proposed restricted main multiverse universe"
2) Checked /etc/apt/preferences.d/proposed-updates, it exists and contains:
Package: *
Pin: release a=wily-proposed
Pin-Priority: 400
3) Run 'sudo apt-get update
4) Run 'sudo apt-get instal --instal-suggests fglrx-updates/wily-proposed fglrx-updates-core/wily-proposed fglrx-amdcccle-updates/wily-proposed lightdm xorg ubuntu-desktop'

However, following these steps, I am told "Release 'wily-proposed' for 'flgrx-<name>' was not found", where <name> is the remaining extension for the 3 packages. Have I managed to add the wrong repositories somehow?