GPG errors

[jw1949]

Trying to
Add
deb http://ppa.launchpad.net/pmcenery/ppa/ubuntu karmic main
to your sources list
in order to (attempt to) connect an iPod Touch, but after a

sudo apt-get update

I have the following errors which I really don't understand - can anybody please advise ?

Errors
W: GPG error: http://dl.google.com testing Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY A040830F7FAC5991
W: GPG error: http://ppa.launchpad.net karmic Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 4EA3A911D48B8E25
W: Duplicate sources.list entry http://ppa.launchpad.net karmic/main Packages (/var/lib/apt/lists/ppa.launchpad.net_chromium-daily_ppa_ubuntu_dists_karmic_main_binary-i386_Packages

Sources list
# deb cdrom:[Ubuntu 9.10 _Karmic Koala_ - Release i386 (20091028.5)]/ karmic main restricted
# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.

deb http://gb.archive.ubuntu.com/ubuntu/ karmic main restricted
deb-src http://gb.archive.ubuntu.com/ubuntu/ karmic main restricted

## Major bug fix updates produced after the final release of the
## distribution.
deb http://gb.archive.ubuntu.com/ubuntu/ karmic-updates main restricted
deb-src http://gb.archive.ubuntu.com/ubuntu/ karmic-updates main restricted

## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team. Also, please note that software in universe WILL NOT receive any
## review or updates from the Ubuntu security team.
deb http://gb.archive.ubuntu.com/ubuntu/ karmic universe
deb-src http://gb.archive.ubuntu.com/ubuntu/ karmic universe
deb http://gb.archive.ubuntu.com/ubuntu/ karmic-updates universe
deb-src http://gb.archive.ubuntu.com/ubuntu/ karmic-updates universe

## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team, and may not be under a free licence. Please satisfy yourself as to
## your rights to use the software. Also, please note that software in
## multiverse WILL NOT receive any review or updates from the Ubuntu
## security team.
deb http://gb.archive.ubuntu.com/ubuntu/ karmic multiverse
deb-src http://gb.archive.ubuntu.com/ubuntu/ karmic multiverse
deb http://gb.archive.ubuntu.com/ubuntu/ karmic-updates multiverse
deb-src http://gb.archive.ubuntu.com/ubuntu/ karmic-updates multiverse

## Uncomment the following two lines to add software from the 'backports'
## repository.
## N.B. software from this repository may not have been tested as
## extensively as that contained in the main release, although it includes
## newer versions of some applications which may provide useful features.
## Also, please note that software in backports WILL NOT receive any review
## or updates from the Ubuntu security team.
# deb http://gb.archive.ubuntu.com/ubuntu/ karmic-backports main restricted universe multiverse
# deb-src http://gb.archive.ubuntu.com/ubuntu/ karmic-backports main restricted universe multiverse

## Uncomment the following two lines to add software from Canonical's
## 'partner' repository.
## This software is not part of Ubuntu, but is offered by Canonical and the
## respective vendors as a service to Ubuntu users.
deb http://archive.canonical.com/ubuntu karmic partner
# deb-src http://archive.canonical.com/ubuntu karmic partner

deb http://security.ubuntu.com/ubuntu karmic-security main restricted
deb-src http://security.ubuntu.com/ubuntu karmic-security main restricted
deb http://security.ubuntu.com/ubuntu karmic-security universe
deb-src http://security.ubuntu.com/ubuntu karmic-security universe
deb http://security.ubuntu.com/ubuntu karmic-security multiverse
deb-src http://security.ubuntu.com/ubuntu karmic-security multiverse
deb http://packages.medibuntu.org/ karmic free non-free
deb http://ppa.launchpad.net/chromium-daily/ppa/ubuntu karmic main
deb http://linux.dropbox.com/ubuntu karmic main
deb-src http://linux.dropbox.com/ubuntu karmic main
deb http://dl.google.com/linux/deb/ testing non-free
deb http://ppa.launchpad.net/pmcenery/ppa/ubuntu karmic main

[MelDJ]

try the link in my sig

[jw1949]

Many thanks, found the PPA help pages very good!