Dependencies to external packages

[A.P. Horst]

   Hi
   I'm rather new to the autotools methodology, and am facing a problem
   where I can't find a solution to.
   I have made two library packages, say bar and foo, where foo is
   dependent on bar. They are both setup with the autotools.
   Now, I can build foo one time successfully when the build directory of
   foo is completely clean, but after that it fails on dependencies to bar
   with a message like:
   make[2]: *** No rule to make target `..../bar_something.h
   ..../bar_something2.h ....' needed by 'foo.o'. Stop.
   foo include only bar.h from which bar_something.h etc. are included.
   The Makefile.am is like this
       # Where to find BAR
       BARLIBS = @barlibs@
       BARINC = @barinc@
       AM_LDFLAGS = ${BARLIBS}
       AM_CPPFLAGS = ${BARINC}
       lib_LIBRARIES = libfoo.a
       libfoo_a_SOURCES = foo.c
       include_HEADERS = foo.h
   So far I figured it discovers bar_something.h as dependencies, which is
   correct, and that this message normally means that the files are
   missing. But the files are truly still there, nothing has changed
   meanwhile.
   I'm not sure if this is the right mailing list to post to, but I would
   really appreciate any help.
   thanks, Arie