You are referring to viewing your album
http://foto-freund.jalbum.net/Meine%20Alben/ on the iPhone using our iOS-app?
That album consists of only folders in the root, and the album.rss-file, which the iOS-app is using to view the album doesn't properly describe those folders. In the album.rss-file they look like thumbnails instead of folders. Were the folders created in a special way?