Quote from ichbincortana on May 28, 2016, 15:27
http://www.track-chinapost.com/de/track?nums=RK363578819CN

13 may Exchange Bureau in Nanjing, has been exported
its now 28 may and not updated yet.

1. May I suggest you contact seller, so he can call China Post: 11185 to find out where is your parcel at.

2. For your country Germany, China Post Airmail Parcel Estimate Arrival Time is 2.5 to 3 weeks.

3. The last tracking i could find is this from China Post:
2016-05-13 11:31:17.0 Nanjing Transit Station export customs cleared
Another tracking is giving me this:
13.05.2016 11:31
Send item abroad (Export)
Nanjing International Place Of Exchange 21004700

4. What I don't know is if Germany Post Office will track your parcel when it arrive in your country? This is what it gave me:
RK363578819CN No information could be found regarding the mail item.

Hope this help.