After about 4 weeks (at 25.07.2014) was no longer the fluorescent lamp. Bought it new at the local electronics shop for 4.00 and the defects can dispose there. The new lamp (OSRAM DULUX S 11 W / 830; Made in Italy) went right away.
So I can because of this "defeat" by purchasing not be satisfied; In addition, the internet price was higher than that of the electric business, which prompted me to be more careful when buying on the Internet in future.