Google Base Not working

Hi:

After reading the post Q: How do I get setup my RSS Feed and Google Base? at http://forum.opencart.com/viewtopic.php?f=138&t=49097

I'm still facing problems as can't see any output in my browser.

Tried with Chrome and IE and the only output I get (after a long wait) is the Opencart 404 "The page you requested cannot be found!". No error, no message...

Using a clean 1.5.6.1 install with a templatemela theme.

Any clue?

Thanks.