distcheck fails (Inclusion confusion)

[Christian Neumair]

I added the following to configure.in:

PYTHON_CFLAGS="-I$PYTHON_PREFIX/include/python$PYTHON_VERSION"
AC_SUBST(PYTHON_CFLAGS)

The problematic Makefile.am contains:

INCLUDES = \
        $(PACKAGE_CFLAGS) \
        $(PYTHON_CFLAGS)

Everything seems to compile fine but a make distcheck reveals:
gcc [...]
-I/home/chris/cvs/gdesklets/gDesklets-0.20/_inst/include/python2.3 [...]
and then fails with Python.h: No such file or directory

What have I done wrong?
Thanks in advance!

regs,
 Chris