Hello: my configure.in : AC_INIT(main, 0.1, zqiang320@xxxxxxxxx) AM_INIT_AUTOMAKE(foreign) AC_PROG_CC AC_PROG_CXX AM_PROG_LIBTOOL AC_OUTPUT(Makefile libsbml/src/Makefile) Makefile.am : bin_PROGRAMS = main SUBDIRS = libsbml/src . main_SOURCES = main.c main_LDADD = sundials/src/cvodes/libsundials_cvodes.la sundials/src/nvec_ser/libsundials_nvecserial.la ./libsbml/src/libsbml.la -lm AM_CPPFLAGS = -Isundials/include -Ilibsbml/include and execute $ make Making all in libsbml/src make[1]: Entering directory `/home/internet/mydoc/test_pj/libsbml/src' ........ -I. -Isundials/include -Ilibsbml/include -g -O2 -MT main.o -MD -MP -MF .deps/main.Tpo -c -o main.o main.c In file included from sundials/include/sundials/sundials_nvector.h:50, from sundials/include/cvodes/cvodes.h:41, from main.c:52: sundials/include/sundials/sundials_types.h:50:38: error: sundials/sundials_config.h: No such file or directory In file included from sundials/include/cvodes/cvodes.h:41, from main.c:52: sundials/sundials_config.h was in directory in sundials/include, why compiler could not find it by AM_CPPFLAGS = -Isundials/include what should I do?