Hoping to annoy not everybody here with my arabic-font-questions.

I have found I nice free arabic ttf-font, you can download it here:
http://fonts.qurancomplex.gov.sa/wp-content/uploads/2012/06/UthmanTN1-Ver10.zip. 


One of its types is: "kfgqpcuthmantahanaskhregular"

If I type in the cmd

C:\Users\Hussein>mtxrun --script font --list --all --pattern=*kf*

I get (together with some other lines/fonts): 
kfgqpcuthmantahanaskhregular kfgqpcuthmantahanaskh 
c:/windows/fonts/UthmanTN1 Ver10.otf

So everything should be ok. But now the following failes:

\definefont[amiri][name:kfgqpcuthmantahanaskhregular*arabic at 17 pt]
\define[1]\Arab{\setupalign[r2l]\amiri#1}
\starttext
\Arab{
بِسْمِ ‏للهِ الرَّحْمَـٰنِ الرَّحِيمِ
}
\stoptext

It compiles, but the output is destroyed, the letters have distances 
between them. See attached pdf. (In other programms, e.g. MS Word that 
does not happen, and the font is set correctly.)

Apart from this mistake, the font is perfect set by context, even the 
"Allah" and its "Kassra" has a nice distance (see the other thread). 
Indeed, if this distace-between-letters problem could be solved, I am 
happy with arabic in context, this font would be enough, and all other 
threads of mine could be closed (as far as I am concerned :))

Thanks for your help!

Huseyin