pipa, things like that happen with packages from Germany to the US too. I've read so much about things missing from packages, especially when they're gifts, but also food (which is legal to ship, so that is not why it's missing)... even sometimes boxes of chocolates where some chocolates would be missing but not all. So it's definitely not just a problem of Deutsche Post
but generally of mailing services, USPS just as much as DP.
I sent some boxes (five of them, two media mail, three ground shipping) from the States to Germany a couple of years ago when I moved, and everything got to Germany just fine, nothing was missing or broken, and they also arrived in the time frame given by USPS. I also paid no customs, but they were all personal items sent from me to me because I moved and as such are not taxed. The ground shipping boxes contained mostly clothes and shoes and stuff like that, the media mail boxes were full of (text) books probably worth $800 when I bought them (though they were used of course). By the way, the lady at the post office in the States told me not to put the value on the boxes. I did have to pick up the boxes at the customs office, they asked what was in the boxes, I told them, they let me go with the boxes without paying anything.