help with magically appearing _OBJECTS variable

[Ben Smith]

Hello, this is the final fatal-ish flaw in my build scripts and I haven't 
determined why it's happening.

I get this warning:
tests/Makefile.am: tester_OBJECTS should not be defined

here's the relevant Makefile.am:

if USING_SDL
if SDL_IMAGE
noinst_PROGRAMS = tester sdl_test
sdl_test_SOURCES = sdl_test.c
sdl_test_LDADD = ../src/libmousetrap.la -lSDL -lSDL_image
endif
else
noinst_PROGRAMS = tester
endif

tester_SOURCES = tester.c
tester_LDADD = ../src/libmousetrap.la

What I want to do is conditionally compile the sdl_test program if USING_SDL 
and SDL_IMAGE are defined by ./configure.  I have the AM_CONDITIONAL statements 
for these two variables working already.  What is a better approach?

I'm currently using automake 1.4-p4, in debian unstable.  I also experience the 
problem with p5, along with some others(libtool related, probably have to 
update it too if I want to use it, eh?) but I don't get the tester_OBJECTS 
warning with automake 1.5(but again, a whole slew of other issues).

I didn't have this problem until I introduced the conditionals in the 
Makefile.am.

Please include me on replies, I'm not subscribed to the automake list.

Thank you,
-b