Hi Steven,
welcome to this board.
There are some guys around here who will be able to answer in english. So keep asking....
In order to get closer to your problem I have got some initial questions for you (I assume you know these points, but just to be sure):
Did you engage the park brake before tattempting to turn the central handle?
The vehicle was haltet completely = 0 km/h?
Ignition is on?
Trunk lid is closed?
If all this is answered with a clear YES then proceed as follows (and please feed back the results here):
1) lock the trunk with your key mechnically. Then test the entire procedure again.
2) check the trunk cable looms (right hand side oom holds: central locking system + necessary status indication for the trunk lid lock)
--> It shall be said at this point that checking the looms is not easy because they usually look fine from outside, but are broken inside. Secondly: In order to check electrically whether or not they are broken you must rise the trunk lid resulting in a different bending angle in the loom bending section near to the hinge. This can result in a working connection which dissapears again when the lid is down... I (and many others here) made this experience and decided to simply exchange the looms with new ones rather than keep testing and testing and guessing and never beeing sure... If you replace the right loom, do not forget to replace the left one as well. Both are the same age... There is a cheap resource for the looms (better quality than oem, really cheap in price: 50 Eur each. Keyword for the search in this board would be FOBA...)
3) follow up for later. Just give it a start....