404 Error with GET trying to access localhost

I've been working on this for a while and can't figure out what I'm
doing wrong...

I'm going (or trying to) through a proxy server and running GET on
other sites.

Trying to access an outside website works fine:
CONNECT www.erights.org:80 HTTP/1.1
HEAD http://www.erights.org/elib/distrib/...Firewalls.html
HTTP/1.1
Host: www.localhost:80

This works fine, gets the page and everything. (About the host, I'mnot
sure what it should be, I've tried <Proxy Server>:<Port>, which didn't
make any difference.

Now, I have a webpage called index.html in a virtual folder called
WebService.

if I try
CONNECT 64.226.92.56:80 HTTP/1.1
which is my local IP adress I never get any response.

However if i try
CONNECT 127.0.0.1:80 HTTP/1.1
or
CONNECT localhost:80 HTTP/1.1
it connects

but when I try
HEAD http://localhost/WebService/index.html HTTP/1.1
Host: www.localhost:80

I get a 404 error. I've tried replacing localhost with my IP adress
and with 127.0.0.1, neither work.

Any idea what I'm doing wrong? (And yes, I've checked just opening
http://localhost/WebService/index.html from by web browser, that works
fine.)

Thanks a lot for any help!
Jervin