maximizing window for MacOSX

[ishi soichi]

MacOSX Snow Leopard

Cocoa Emacs 23.2.1

I am trying to develop an Emacs Lisp program that maximizes the window.

I found and modified the following code, which was originally for Carbon Emacs.

(when (eq window-system 'ns)

  (add-hook 'window-setup-hook

            (lambda ()

              (set-frame-parameter nil 'fullscreen 'fullboth)

              )))

(defun mac-toggle-max-window ()

  (interactive)

  (if (frame-parameter nil 'fullscreen)

      (set-frame-parameter nil 'fullscreen nil)

    (set-frame-parameter nil 'fullscreen 'fullboth)))

It does not act as I want it to.

window-system for MacOSX is "ns" I believe. 

Could anyone see why it does not work?

Thanks in advance.

soichi