XML RPC – XML RPC

Hi,

I have research wordpress core files and found that to make media for wordpress post as featured image i need this query wp_post_thumbnail if i use metaWeblog.newPost. But the problem is this function not works. i use this code:
'wp_post_thumbnail' => '29'
Tell me do i am doing somthing wrong, after posting artickle i the featured image is not in place even if it uploaded correctly into media and id provided correctly which is 29 in my above example.

let me know plz.

Thanks,
Turkel.