Fail to use nglib


I downloaded NGsolve binary (v 6.2.2304). I downloaded Python 3.7. The binary netgen works fine but I wanted to use nglib.lib without using the interface.

So I created an empty Visual Studio 2017 project and copied the file ng_stl.cpp from here as my main file.
Eventhough I included nglib.h and nblig.lib in the project properties, I have an error for every NGLIB_API in nglib.h. I cannot compile my project. It seems that every function in nglib.h with NGLIB_API is not defined in ng_stl.cpp. Is there some compiling properties that I forgot to add ?