[XeTeX] Arabxetex, Transiteration

[Mohammad Gharaibeh]

Dear Fokls,

I'am sorry to repeat my question again, but untill now 
nobody has answered how to transliterate with arabxelatex.
Berteun has allready helped me with the overlining 
problem, thank you very much.

Although I followed the instruction of the documentation, 
the transliteration didn't work.
moreover the transliteration should follow the rules of 
DMG.

here the example:

\documentclass[12pt,a4paper]{book}
\usepackage{arabxetex}
\newfontfamily\arabicfont[Script=Arabic, 
Scale=1.5]{Scheherazade}
\SetTranslitConvention{dmg}
\begin{document}
\begin{arab}[trans]
al-^say_h al-`Alim \UC na.sIr \UC al-dIn \UC al-.tUsI
\end{arab}
\end{document}

what did I do wrong?

regards
Mohammad Gharaibeh