Please, help with AM_CONDITIONAL

[Jose Roman Bilbao]

Hi all,

I am having a problem when trying to build a program conditionally. It
is a problem with the macro that detects a specific library (TIFF). This
macro makes a definition of HAVE_LIBTIFF:

 AC_DEFINE(HAVE_LIBTIFF)
 AM_CONDITIONAL(AM_TIFF, test $have_tiff = yes)

Those lines are within an m4 macro and my question is... 

Will AM_TIFF be usable from my Makefile.am?:

OPTIONAL_PROGS =

if BUILD_MPI
OPTIONAL_PROGS += MPIArt MPI_WBP 
endif

if BUILD_OGL
OPTIONAL_PROGS += Phan3D
endif

if AM_TIFF
OPTIONAL_PROGS += Tiff2Raw 
endif

Or, on the other hand, should I make another AM_OPTIONAL in my
configure.ac source? In this case, what should I write? I am using this
and does not work at all (Changing BUILD_TIFF for AM_TIFF in
Makefile.am):

#Checking for TIFF library as well as some of its capabilities
AC_CHECK_LIBTIFF
AM_CONDITIONAL(BUILD_TIFF, HAVE_LIBTIFF )

Thanks in advance