l4/sys/syscalls.h: No such file or directory

Hi, I'm using the following example provided by Michael Hohmuth in 2000 to create new tasks and threads: http://os.inf.tu-dresden.de/pipermail/l4-hackers/2000/000384.html I've placed the code in a copy of the hello example, but added

REQUIRES_LIBS = l4sys to the Makefile. The directory structure is located at './l4/pkg/taskcreat'.

Nevertheless, compilation is terminated due to a fatal error:

./l4/pkg/taskcreat/server/src/main.c:5:29: fatal error: l4/sys/syscalls.h: No such file or directory

Why is syscalls.h missing here? Best regards, Valentin