Just tried to add Backports and got this error:

[Daminator]

W: Couldn't stat source package list http://archive.ubuntu.com breezy-backports/main Packages (/var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_breezy-backports_main_binary-i386_Packages) - stat (2 No such file or directory)
W: Couldn't stat source package list http://archive.ubuntu.com breezy-backports/restricted Packages (/var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_breezy-backports_restricted_binary-i386_Packages) - stat (2 No such file or directory)
W: Couldn't stat source package list http://archive.ubuntu.com breezy-backports/universe Packages (/var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_breezy-backports_universe_binary-i386_Packages) - stat (2 No such file or directory)
W: Couldn't stat source package list http://archive.ubuntu.com breezy-backports/multiverse Packages (/var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_breezy-backports_multiverse_binary-i386_Packages) - stat (2 No such file or directory)

When I open Synaptic Package Manager.
Tried adding the lines from the sticky post, and also tried just uncommenting the backport sections that were already in the file, but get the sime kind of erroy with each, so I've returned the file to how it was until I figure out what's going on.

[invalid]

sudo apt-get update

Cheers,
Cb

[Mustard]

You will need to close synaptic too, before you do the above command or it will give you a lock file error.

[Daminator]

Great, thanks for that!

[mvandeg]

sudo apt-get update

Cheers,
Cb

Hitting Reload from within Synaptic a second time, also works and is even easier.