update problem

[skkmaths]

when i do update i get this error
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 7274A4DAE80D6BF5
i use ubuntu 10.04..please help me..

[dino99]

if you use a ppa repo, first read how to use it, all is explained

[dino99]

https://launchpad.net/ubuntu/+ppas