[OS X Emacs] Customizing fonts

[albler]

Hi,

I'm changing the default appearance of my frames by adding the
following to Preference.el

(setq default-frame-alist
      '((background-color . "black")
	(foreground-color . "green")
	(width . 80) (height . 100)
	(font . "-apple-andale mono-medium-r-normal--0-0-0-0-m-0-mac-roman")))

All but the font command work. The font exists because I manage to
change a frame by hand using C-x set-frame-font.

Any suggestions?

Thanks,
Alberto.