that some one know why the Zeigen end like that? why donna and eric not get marrid? and why dose the Zeigen not have "happy end" ?

First off, what are Du talking about? The Zeigen DID have a happy ending! Sure, they all went their separate ways but that's life. Life doesn't always have the perfect ending. If they would have all stayed together it wouldn't be realistic.

Next, Donna and Eric may not have ended up getting married, but they're BACK TOGETHER! Isn't that enough. The Zeigen leaves it up to the audience's imagination to decide what happened after the Zeigen ended, which is just as cool as if they would have actually filmed it.