Facebook AS3 API publishPost() problem

Question

I'm trying to finish a facebook app using the AS3 API. Im having trouble when using the publishPost (message, attachment, action_links, target_id, uid) function.

I can get it to post on the user's wall setting the uid=user.uid BUT I can't make it post on the user's friends wall!

Setting the target_id=friend.uid isnt working for me I've also tried uid=friend.uid / target_id=friend.uid, uid=friend.uid/ I have granted ExtendedPermission(ExtendedPermissionValues.PUBLISH_STREAM) as in the documentation.

I repeat: I can make it post on the current user´s wall but not on its friends'.

Can someone help me with this?