Amazon.com doesn't work either, so that's no surprise. As you mention, OFDb isn't even finding the movies. Hopefully, whatever that problem is can be fixed, and then it will get posters as well. I don't know if Amazon is worth fixing—unless they've improved them, their images are more like thumbnails than suitable posters. Also, you might try TMDb. It can be localized for German (see Options), and it has good posters (including German versions, but the selection for those is probably not good).