problem with" freebsd-update-upgrade.tgz.asc"

[alasdair at iprimus.com.au]

Hi,
 I have downloaded the above script from http://www.daemonology.net/blog/2007-11-11-freebsd-major-version-upgrade.html

Installed gpg all set up ok AFAICT.

put the freebsd security officer's public key on my gpg keyring . 

Used the following command to verify the file:
localhost# gpg --verify freebsd-update-upgrade.tgz.asc freebsd-update-upgrade.tgz
gpg: can't open signed data `freebsd-update-upgrade.tgz'
gpg: can't hash datafile: No such file or directory
localhost# 

AFAICT the public key is ok 


pub   1024D/CA6CDFB2 2002-08-27
uid                  FreeBSD Security Officer <security-officer at FreeBSD.org>
sub   2048g/A3071809 2002-08-27

Apart from the fact that the file could be dodgy (?) What could be the problem?

Have I used the wrong key? I imagine the error msg would be different if
that was the case.

Thanks,

Alasdair