Shell Programming and Scripting

When I run autogen.sh(the auto hell stuffs+configure) and type "make distclean", I get a proper result(which can be built).
However, when running autogen.sh and then "make distcheck", I get an error:
...

Code:

rm -f Makefile
ERROR: files left in build directory after distclean:
./src/MediaPlayer.c
./src/GNOME_MPRIS_Applet_vala.stamp
./src/MasterDBus.c
./src/TrackList.c
./src/PlayersList.c
./src/MainApplet.c
./src/Player.c
./src/main.c
./src/PlayerAbilities.c
make[1]: *** [distcleancheck] 1 הלקת
make[1]: Leaving directory `/home/tal/Projects/MPRIS_Applet/GNOME_MPRIS_Applet/gnome-mpris-applet-0.0.1/_build'
make: *** [distcheck] 1 הלקת

Other than that, everything works like magic. But if distcheck say something is wrong, he probably right.
Also, you shell noticed than this scripts compile from vala language if compiler exist, otherwise it use C compiler.
(Vala compiles first to C, and then to binaries)
So, why it keeps failing?

My work(108 kb):gnome-mpris-applet-0.0.1.tar.bz2

I am working on this bro hold on

Thanks, someone has already given me the answer.
For it work perfectly, change the if statement in src/Makefile.am to this:
if USE_VALA
GNOME_MPRIS_Applet_PACKAGES=@applet_PACKAGES@
GNOME_MPRIS_Applet_SOURCES = \
$(GNOME_MPRIS_Applet_VALASOURCES)

VALAFLAGS= \
$(GNOME_MPRIS_Applet_PACKAGES)
else
GNOME_MPRIS_Applet_SOURCES = \
$(GNOME_MPRIS_Applet_VALABUILTSOURCES)
endif

And remove the "GNOME_MPRIS_Applet_SOURCES" deceleration after the if.