Couldn't access keyring

[linux china <chinalinux@gmail.com>]

Hi,

My source.list just contains a simple line "deb
http://ftp.debian.org/debian/ etch main", could anyone tell what's
below problem ?

debian:/etc/apt# apt-get update
Get:1 http://ftp.debian.org etch Release.gpg [1032B]
Hit http://ftp.debian.org etch Release
Err http://ftp.debian.org etch Release

Get:2 http://ftp.debian.org etch Release [67.8kB]
Ign http://ftp.debian.org etch Release
Ign http://ftp.debian.org etch/main Packages/DiffIndex
Hit http://ftp.debian.org etch/main Packages
Fetched 68.8kB in 9s (7327B/s)
Reading package lists... Done
W: GPG error: http://ftp.debian.org etch Release: Couldn't access keyring: 'No s
uch file or directory'
W: You may want to run apt-get update to correct these problems