2 Smoke detectors were defective! Enter every 30 sec. A beep from! In the "test button" they do not respond! Before I wrote this review, I called the service of Messrs. Claus GmbH! I was about 25 minutes on hold and was able to speak with any staff! To rule out that the problem comes from the batteries (9 V), I bought two new! The error is still present!
Addendum: Today on 01.03.2015 I got a replacement for the first defective fire alarm! This worked perfectly!