lighttpd+fcgi can't auto load metal?

my server used lighttpd and fcgi

RAILS_ROOT/app/metal/poller.rb
#### class Poller

def call(env)
  if env["PATH_INFO"] =~ /^\/poller/
    [200, {"Content-Type" => "text/html"}, "Hello, World!"]
  else
    [404, {"Content-Type" => "text/html"}, "Not Found"]
  end
end

end ####

I start WEBrick server on localhost is ok
$curl http://localhost:3000/poller return "Hello, World!"

but i remote access : http://www.mydomain.com/poller
it's return "404 Not Found"

why? Can not auto load metal on fcgi?