problem with updating a static library using make/makefiles

[Thomas Lavergne]

Hi all;
I am not an expert with GNU make and makefiles. However, after oneday of 
documenting and testing, I still cannot see what is wrong with my case.
I want to build a static library libfray.a (using GNU ar 2.13.90) which 
is  just an archive of .o files. These 80 .o files are located in 
various subdirectories. So, at libfray.a_level I have a Makefile which 
basically list my subdirectories, cd to each of them and execute MAKE:

Makefile at libfray.a level :
--------------------------
MAKE = make -$(MAKEFLAGS)
STUFF = libsource libintera libfilter libcommon libmeasure libobj libdistr
SHELL = /bin/sh

default:
   for i in $(STUFF); do \
       (cd $$i && $(MAKE)); \
       (/usr/bin/ranlib libfray.a);\
   done
------------------------------------

Then, on each subdirectory (stuff) I have a similar make file:
--------------------------------
LIB = ../libfray.a
INCLUDE = -I.. -I../..
CFLAGS = $(CCFLAGS) $(INCLUDE) $(OPTIMIZE)
ARFLAGS=qv

SHELL = /bin/sh

CFILES = filter.c hit.c howend.c interange.c range.c
OFILES = $(CFILES:.c=.o)

$(LIB): $(OFILES)
   ar $(ARFLAGS) $(LIB) $(OFILES)
--------------------------------------------

The rule $(LIB) seems to be the default rule for make (there is a make 
depend annd make clean but they are at the bottom of the Makefile)

NOW, when I execute the make command (GNU make 3.79.1 built for Linux 
Red Hat 9) from libfray.a level, all my subdirectories are effectively 
browsed and I can see all the 80 .o files created. BUT for a reason I 
ignore, the ar command is not always called to update the ../libfray 
target. The situation is not at all stable : if I 'make clean' to erase 
all .o and the libfray.a (i checked it is done) and I rebuild my library 
('make' at libfray.a level), it will be another subdirectory which will 
not be included.. If I modify the order of STUFF to browse my 
subdirectories, another subdirectory will not be included.

I tried a 'make -d' from the libfray.a level. The implicit rules for 
compiling .c into .o are working fine but I will list what happens for 
the not-included-in-the-static-library directory:

Finished prerequisites of target file `../libfray.a'.
Prerequisite `filter.o' is newer than target `../libfray.a'.
Prerequisite `hit.o' is newer than target `../libfray.a'.
Prerequisite `howend.o' is newer than target `../libfray.a'.
Prerequisite `interange.o' is newer than target `../libfray.a'.
Prerequisite `range.o' is newer than target `../libfray.a'.
No need to remake target `../libfray.a'.

How is it possible that prerequisites newer than target do not imply the 
remake of the target??
If it is possible, then please indicate me what are the possible 
situations so that I can check everything.

Thanks for any help,
thomas