Makefile help needed

[David Kramer]

My makefile is *mostly* working.

My problem is this:  I want to build a .o in a different directory from the 
current one, and it's being rather stubborn unless I spell out the rule.

Imagine if you will, a makefile that can build target1, target2, and 
target3, and I'm adding troubletarget.o to it.  Assume troubletarget.c is in 
the currect directory with everything else

If I do:
all: target1 target2 target3 troubletarget.o
it builds fine.

If I do:
all: target1 target2 target3 ./troubletarget.o
it builds fine.

If I do:
all: target1 target2 target3 ../otherdir/troubletarget.o
I get "make: *** No rule to make target ../otherdir/troubletarget.o"
which I can understand, because it doesn't know where the C file is.

HOWEVER, if I do:
all: target1 target2 target3 ../otherdir/troubletarget.o
it simply does not try to build it at all.

If I add a rule like:
../otherdir/troubletarget.o: troubletarget.c
it still doesn;t attempt to build it.

If I change that to
../otherdir/troubletarget.o: troubletarget.c
	$(CC) $(CFLAGS) -c $< -o $@
it works, but I don't see why I have to do that, since it already knows how 
to turn a .c into a .o, because earlier in the file I have
.c.o:
	$(CC) $(CFLAGS) -c $< -o $@
which should build it fine,

Note that I can't use the newer style
%.o : %.c ; command...
because the stem is different on the .o and the .c since they're in 
different directories.


Does this make sense?  What am I doing wrong?  Thanks in advance.