[XeTeX] XeTeX on Debian

[Kia Teymourian]

Hi,
i installed the XeTeX on a Debian Linux system and could use the xetex 
commad to create a sample file
in persian language, very thing seems to be OK

http://www.linuxiha.com/Persian-XeTeX/persian-xetex.tex
http://www.linuxiha.com/Persian-XeTeX/persian-xetex.pdf

But now I can not use "texexec" to compile an article, and get this error:
--------------------------------------------------------------
kia at thinkpad:~/XeTeX/docs/Samples$ texexec Kia_Article.tex

 TeXExec 5.2.4 - ConTeXt / PRAGMA ADE 1997-2005

            executable : xelatex
                format : cont-en
             inputfile : Kia_Article
                output : standard
             interface : en
          current mode : none
               TeX run : 1

This is XeTeX, Version 3.141592-2.2-0.995 (Web2C 7.5.5)
 (WARNING: translate-file "natural.tcx" ignored)
---! /var/lib/texmf/web2c/cont-en.fmt was written by pdfetex
(Fatal format file error; I'm stymied)

           return code : 256
              run time : 1 seconds

        total run time : 1 seconds
---------------------------------------------------------------


Should I add "/var/lib/texmf/web2c/cont-en.fmt" to some System variables?

Best regards,
Kia Teymourian