Sample.h:41:40: fout: ‘Slice’ was not declared in this scope

make -C dpf/dgl
make[1]: Map '/home/rob/git/plugin-examples/dpf/dgl' wordt binnengegaan
make[1]: Er hoeft niets gedaan te worden voor 'all'.
make[1]: Map '/home/rob/git/plugin-examples/dpf/dgl' wordt verlaten
make all -C plugins/Slicer
make[1]: Map '/home/rob/git/plugin-examples/plugins/Slicer' wordt binnengegaan
g++ Slice.cpp -Wall -Wextra -pipe -fPIC -DPIC -DNDEBUG -O2 -ffast-math -mtune=generic -msse -msse2 -fdata-sections -ffunction-sections -mfpmath=sse -fvisibility=hidden -DHAVE_JACK -DHAVE_LIBLO -std=c++0x -std=gnu++0x -fvisibility-inlines-hidden  -I. -I../../dpf/distrho -I../../dpf/dgl -MD -MP -c -o Slice.cpp.o
In file included from Slice.h:3:0,
                 from Slice.cpp:1:
Sample.h:41:40: fout: ‘Slice’ was not declared in this scope
         void createSlices( std::vector<Slice>* slices, int number);
                                        ^~~~~
Sample.h:41:45: fout: template argument 1 is invalid
         void createSlices( std::vector<Slice>* slices, int number);
                                             ^
Sample.h:41:45: fout: template argument 2 is invalid
make[1]: *** [../Makefile.mk:79: Slice.cpp.o] Fout 1
make[1]: Map '/home/rob/git/plugin-examples/plugins/Slicer' wordt verlaten
make: *** [Makefile:19: plugins] Fout 2