[XeTeX] font not found

[Yves Codet]

Hello.

I'm unable to use Devanagari MT with the following commands:

\usepackage{fontspec}
\setromanfont[Ligatures=Rare,BoldFont={Devanagari MT 
Bold},ItalicFont={Devanagari MT Bold},BoldItalic={Devanagari MT 
Bold}]{Devanagari MT}

I get this error message, which I don't understand:

! Font \zf at fonttwo="Devanagari MT" at 10.0pt not loadable: installed 
font not f
ound.
\ifEqFonts ...fi \font \zf at fonttwo = "#2" at 10pt
                                                   \edef \@tempb 
{\fontname \...
l.3 ...Italic={Devanagari MT Bold}]{Devanagari MT}

?                                                   \zf at aatfalse 
\zf at opentypef...
l.3 ...Italic={Devanagari MT Bold}]{Devanagari MT}

?

Here is a short sample, in case it may help to locate the problem:

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\documentclass[a4paper,12pt]{book}
\usepackage{fontspec}
\setromanfont[Ligatures=Rare,BoldFont={Devanagari MT 
Bold},ItalicFont={Devanagari MT Bold},BoldItalic={Devanagari MT 
Bold}]{Devanagari MT}
\catcode"00A0=\active
\def^^^^00a0{\char32\relax}
\renewcommand{\baselinestretch}{1.4}
\hbadness=10000
\vbadness=10000

\title{}
\author{}
\date{}

\begin{document}
%\maketitle

\begin{center}
{\small ॐ नमश्चिदात्मपरमार्थवपुषे  ॥}\\
अथ\\
\vspace{4ex}
{\LARGE\textbf{परमार्थसारः}}\\
\vspace{4ex}
श्रीमन्महामाहेश्वराचार्यवर्यश्रीमदभिनवगुप्ताचार्यविरचितः  ।\\
\vspace{2ex}
श्रीमद्योगराजाचार्यकृतविवृत्युपेतः  ।
\end{center}

\bigskip
\begin{verse}
चिद्घनोऽपि जगन्मूर्त्या श्यानो यः स जयत्यजः ।\\
स्वात्मप्रच्छादनक्रीडाविदग्धः परमेश्वरः  ॥ १  ॥
\end{verse}

\begin{verse}
योऽयं व्यधायि गुरुणा युक्त्या परमार्थसारसंक्षेपः ।\\
विवृतिं करोमि लघ्वीमस्मिन्विद्वज्जनार्थितो योगः ॥ २ ॥
\end{verse}

इह शिवाद्वयशासने देहादिप्रमातृताप्राधा%
\end{document}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

Thanks in advance for your help :)

Best wishes,

Yves