I have problem with RTL for Persian language in Emacs

the letters that I'm writing in emacs  is separated!! (see wrongbidipersian.png)

The correct form of lines are in correctbidipersian.png (in attachments)

I'm using GNU/Linux with latest version of linux kernel

latest development snapshot of emacs24 from repository

variables:

C-h H showing that Arabic bidi not working (see emacs-languages.png in attachments)

Font that I'm using : Sans

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