[XeTeX] hyphenation problem

[Mehdi Omidali]

Hi all,
In farsi we have words like 
می‌بینم
and there is no space between ی and ب. In a standard farsi keyboard layout, we
use Shift+B to put a zero-width space between these two characters 
(unless we get میبینم). 
I can simply do it in the body of my file and xetex shows it correct
but when I use 
\hyphenation{می‌-بینم}

(where after ی there is a Shift+B) then I got an error that says 
می‌ب not a character.
Thanks