Make Error when building project and Python API

**Hello,**

I follow the instructions on the main site trying to use the Python demo. These are the commads I have entered so far:
```
~/git clone --recursive https://github.com/andrewssobral/simple_vehicle_counting.git
~/cd simple_vehicle_counting
~/simple_vehicle_counting/cd build
~/simple_vehicle_counting/build/ cmake ..
~/simple_vehicle_counting/build/make -j 8
```
However, when running the 'make' command (and when trying to build the normal C version, the same error shows up), it fails with Error 2. Here is the end of the output:
```
...
/home/tamas/simple_vehicle_counting/package_tracking/cvblob/cvcontour.cpp:378:3: warning: control reaches end of non-void function [-Wreturn-type]
}
^
/home/tamas/simple_vehicle_counting/package_tracking/cvblob/cvlabel.cpp: In function ‘cvb::CvLabel cvb::cvGetLabel(const IplImage*, unsigned int, unsigned int)’:
/home/tamas/simple_vehicle_counting/package_tracking/cvblob/cvlabel.cpp:442:3: warning: control reaches end of non-void function [-Wreturn-type]
}
^
CMakeFiles/simple_vehicle_counting.dir/build.make:230: recipe for target 'CMakeFiles/simple_vehicle_counting.dir/package_tracking/cvblob/cvlabel.cpp.o' failed
make[2]: *** [CMakeFiles/simple_vehicle_counting.dir/package_tracking/cvblob/cvlabel.cpp.o] Error 1
make[2]: *** Waiting for unfinished jobs....
CMakeFiles/Makefile2:67: recipe for target 'CMakeFiles/simple_vehicle_counting.dir/all' failed
make[1]: *** [CMakeFiles/simple_vehicle_counting.dir/all] Error 2
Makefile:83: recipe for target 'all' failed
make: *** [all] Error 2
```
What is the problem and how can I fix it? Or how can I modify the Python code so that I don't have to actually build the project?

_Thanks for the answers in advance!_