C++ include libary OSX, clang, ld: symbol(s) not found for architecture x86_64

i'm trying to develop a small scaled application to exchange data between a pc and a plc using the snap7 Libary.

I installed snap7 via brew and edited my cmake with the following lines

include_directories(/usr/local/Cellar/snap7/1.4.2_1/include)
link_directories(/usr/local/Cellar/snap7/1.4.2_1/lib)

so far so good i can now do this

#include <snap7.h>

but when i try to build the application (using CLion on macOS 10.13.3 with XCode Version 9.2 (9C40b)

i get the following error

Undefined symbols for architecture x86_64:
  "TS7Client::TS7Client()", referenced from:
  _main in main.cpp.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make[2]: *** [Zebra_TCP] Error 1
make[1]: *** [CMakeFiles/Zebra_TCP.dir/all] Error 2
make: *** [all] Error 2