AC_ARGS_ENABLE default behaviour not working

[jling]

Hello, I'm at a loss as to why the following is not working.  I can 
only get program1 to be generated if I specifically run:

configure --enable-toolbox

But if I just do a:
configure

I don't get the program built.  Isn't the default behaviour, to build 
in this case, based on what I have below?

In my configure.ac:
AC_ARG_ENABLE(toolbox,
                [  --enable-toolbox   Build Atlas toolbox applications],
                [case "${enableval}" in
                    yes) toolbox=true ;;
                    no)  toolbox=false ;;
                    *)   AC_MSG_ERROR(bad value ${enableval} for --
enable-toolbox) ;;
                esac],
                [toolbox=true])
AM_CONDITIONAL(TOOLBOX, test "$enable_toolbox" = yes)

Then in my Makefile.am:

bin_PROGRAMS =
if TOOLBOX
bin_PROGRAMS += bin/program1
endif
...


Thanks in advance,
John Ling