my $invdate = $form->{invdate} eq 'undefined' ? undef : $form->{invdate};
my $duedate = $form->get_duedate(\%myconfig, $invdate);
- print $form->ajax_response_header() . $duedate;
+ print $form->ajax_response_header() . ($duedate || $invdate);
$main::lxdebug->leave_sub();
}