How To Post Photo To Album In Facebook Graph Api

i wrote an application for facebook but i couldn't upload image to album that i created,
code is in below

Facebook.FacebookAPI api = new Facebook.FacebookAPI(GetAccessToken());
Dictionary<string, string> album = new Dictionary<string, string>();
album.Add("name", "Test Album");
album.Add("message", "Message here!");
JSONObject result = api.Post("me/albums", album);
string AlbumId = result.Dictionary["id"].String;
Dictionary<string, string> photo = new Dictionary<string, string>();
photo.Add("message", "test Message");
photo.Add("source", "tgw.jpg");
JSONObject photoResult = api.Post("/" + AlbumId + "/photos", photo);