[pstricks] \definecolor undefined

[Alberto Vecchiato]

Hi, I'm trying to run the "Tore3D.tex" example downloaded from
http://www.tug.org/applications/PSTricks/ThreeD/ but the file doesn't compile
and I get the following error message:
! Undefined control sequence.
l.17 \definecolor
                 {LightBlue}{rgb}{0.68,0.85,0.9}

Here is the first lines of the original source code:
\documentclass{article}

\usepackage{pstricks}             % PSTricks with the `color' extension
\usepackage{pst-node}           % PSTricks package for nodes
\usepackage{pst-3d}             % PSTricks package for 3d graphics

% Definition of new colors
\definecolor{LightBlue}{rgb}{0.68,0.85,0.9}
\definecolor{Salmon}   {cmyk}{0,0.53,0.38,0}
...

It seems that my version of pstricks lacks of some 'color' extemsion mentioned
in the line where pstricks is loaded. Or is it simply an outdated example?

Thanks in advance

Alberto Vecchiato