I want to upgrade gnome-power-manager (g-p-m) to the following version: g-p-m 2.22.0-0ubuntu1 (or any later versions)

The reason is because this version fixes the problem of the screen brightness resetting to maximum (https://bugs.launchpad.net/ubuntu/+s...er/+bug/137598)

Here's what I did:

1. In Synaptic, I upgraded the list of packages by pressing Ctrl-R.
2. I searched for the gnome-power-manager package. However, 2.20.0-0ubuntu6 is the package that is shown. I am not able to see any higher versions.
3. Alternately, I select gnome-power-manager, right-click and try to select "Mark for upgrade". But I cannot click the since "Mark for upgrade" button appears grey.

Please help.