How do I upload a photo to a friend's wall?

I am using the Facebook C# SDK (Graph API) and I am able to post photos to the logged-in user's wall ('me'), but when trying to replace the 'me' with one of the logged-in user's friends id, it still posts the photo to the logged开发者_如何学Go-in user's wall instead to the friend's wall, using this code:

fb.PostAsync("selecteFriendIDHere/photos", parameters);