@LTLIBOBJS@ seen but never set in `configure.in' - why?

[Vadim Zeitlin <Vadim.zeitlin@dptmaths.ens-cachan.fr>]

 Hello,

 I'm new to automake so sorry for this possibly stupid question, but
I seem unable to figure out why does automake give me this warning.

 I have 2 lines

        libwx__WX_LIBRARY__la_SOURCES = ...base sources...
        libwx__WX_LIBRARY__la_LIBADD = $(LTLIBOBJS)

in my Makefile.am where the base sources are the files which are
always compiled into the library and LTLIBOBJS is supposed to contain
any additional files (there are plenty of --enable-foo options which,
in general, add foo.lo to LTLIBOBJS).

 When I run automake (1.4) I get the warning (which is, in fact, an error
because it returns non zero exit code) in the subject line. Looking
at the automake code, it seems like it wants me to have

        LIBOBJS="$LIBOBJS whatever.o"

in my configure.in - so I inserted such line to make it happy, but I
don't think it's the right solution :-/

 Is it normal that LTLIBOBJS="LTLIBOBJS foo.lo" is not enough to it?
Is it a bug in automake or (as I suspect) am I completely missing
something?

 Thanks in advance for any help,
VZ