gnuplot doesn't work for Emacs+imaxima



I have recently installed Maxima + imaxima.
Although certainly I have also gnuplot, it does not plot at all.

The environment is:
MacOSX Snow Leopard
Cocoa Emacs23.2
Maxima5.25
gnuplot 4.5
Ghostscript3.6.9

By double-clicking the icon shown in "Finder" will activate gnuplot, Maxima,
and Ghostscript.  But the problem arises when using with Emacs.

in .emacs setting,

;; maxima
(setq exec-path
(append (list
"/Applications/Maxima.app/bin"
"/Applications/Emacs.app/Contents/Resources/lisp/imaxima-imath/"
"/Applications/gnuplot.app/bin"
"/Applications/Ghostscript.app/bin"
"/Applications/teTeX.app/bin") exec-path))
(add-to-list 'load-path
"/Applications/Emacs.app/Contents/Resources/lisp/imaxima-imath/")
(setq imaxima-latex-preamble "\\usepackage{eulervm}")
;;; add autoload of imaxima and imath.
(autoload 'imaxima "imaxima" "Image support for Maxima." t)
(autoload 'imath "imath" "Interactive Math mode" t)
;;----------------------------------

When imaxima started, it shows,

;Compiler warnings for
"/Applications/Emacs.app/Contents/Resources/lisp/imaxima-imath/imaxima.lisp"
:
;   In BREAK-DBM-LOOP inside an anonymous lambda form: Undefined function
$FRAME
Maxima 5.25post http://maxima.sourceforge.net
using Lisp Clozure Common Lisp Version 1.7-dev-r14869  (DarwinX8664)

at the top of the buffer.  I'm not sure if it's important.

Normal calculations, such as arithmetics and calculus, seem fine.
But when typing "plot2d(sin(x),[x,-%pi/2, %pi/2]);", it will open a buffer
"*imaxima gs output*" which is empty.

Could anyone point out where the problem is?

soichi