no key then get key

when i run this

sudo apt-get update

i got this

W: GPG error: http://ppa.launchpad.net lucid Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 6E871C4A881574DE

i google and it leads me to here
to fix this. run

gpg --keyserver subkeys.pgp.net --recv 6E871C4A881574DE

and this

gpg --export --armor 6E871C4A881574DE | sudo apt-key add -

then try again

sudo apt-get update

ayem so lazy these days, this error been encountered for like few days already.
happy luciding everyone!