@SGaist @hskoglund @belab @Franckynos
Thank you for helping me!
You were right, I did not import the symbols.
I added this :
#ifdef GAME_EXPORTS
# define GAME_API __declspec(dllexport)
#else
# define GAME_API __declspec(dllimport)
#endif
to my DLL code and now everything works.
Have a nice day, you rock! :-)