On the submit page, it results in a blank page. No error. Just a blank page. Is this something to do with the custom theme I’m using instead of the default bp 1.2.3 theme? Any workaround this?

/* Copyright 2009

James Pegram (email : jwpegram [make-an-at] gmail [make-a-dot] com)
Alexander Grau (email : alex [make-an-at] grauonline [make-a-dot] de)

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/

if ( !class_exists( ‘wpmuBlockSpamByMath’ ) ) {
class wpmuBlockSpamByMath {

// Constructor
function wpmuBlockSpamByMath() {

// WPMU specific actions/filters
add_action(‘wpmu_options’, array( &$this, ‘blockspam_site_admin_options’));
add_action(‘update_wpmu_options’, array( &$this, ‘blockspam_site_admin_options_process’));
add_action(‘wp_head’, array( &$this, ‘blockspam_stylesheet’) );
add_action( ‘signup_extra_fields’, array( &$this, ‘wpmu_add_hidden_fields’ ) );
add_action( ‘bp_before_registration_submit_buttons’, array( &$this, ‘wpmu_add_hidden_fields’ ) );

add_filter(‘wpmu_validate_user_signup’, array( &$this, ‘wpmu_validate_user_signup’ ) );
add_filter(‘bp_before_current_signup_step’, array( &$this, ‘wpmu_validate_user_signup’ ) );
add_filter(‘signup_blogform’, array( &$this, ‘wpmu_add_hidden_blogfields’ ) );

// We don’t want this filter applied if we’re outside of the initial MU signup process (ie: don’t apply it to the wp-ativate function calls).
if ($_POST['stage'] != ‘validate-user-signup’) { remove_filter(‘wpmu_validate_user_signup’,array( &$this, ‘wpmu_validate_user_signup’ ) ); }
}

// Initialize plugin
function init() {
if ( function_exists( ‘load_plugin_textdomain’ ) ) {
load_plugin_textdomain( ‘wpmu-block-spam-by-math’, PLUGINDIR.’/’.dirname(plugin_basename(__FILE__)) );
}
}

// Protection function for submitted comment form
function wpmu_validate_user_signup( $content ) {
$this->wpmu_check_hidden_fields();
return $content;
}

// Add hidden fields to the signnup form
/* function wpmu_add_hidden_fields() {
$mathvalue0 = rand(2, 15);
$mathvalue1 = rand(2, 15);
echo ‘IMPORTANT! To be able to proceed, you need to solve the following simple math (so we know that you are a human) ‘;
echo “What is $mathvalue0 + $mathvalue1 ?”;
echo ”;
echo ”;
echo ‘Please leave these two fields as-is: ‘;
echo “”;
echo “”;
echo ”;
}
*/

//add to the constractor values for this …
//or change + to minus altogether
// Add hidden fields to the signnup form

function wpmu_add_hidden_fields() {
$mathvalue0 = rand(10, 20);
$mathvalue1 = rand(1, 10);
echo ‘IMPORTANT! To be able to proceed, you need to solve the following simple math (so we know that you are a human) ‘;
echo “What is $mathvalue0 – $mathvalue1 ?”;
echo ”;
echo ”;
echo ‘Please leave these two fields as-is: ‘;
echo “”;
echo “”;
echo ”;
}

// Pass the hidden fields to the blog form
function wpmu_add_hidden_blogfields() {
if ( !empty( $_POST['mathvalue0']) && !empty($_POST['mathvalue1'] ) && !empty($_POST['mathvalue2'])) {
echo “”;
echo “”;
echo “”;
}
}

function blockspam_stylesheet() {
?>

.mu_register .error {font-size: 12px; margin:5px 0; }
.mu_register #spambot {font-size: 12px; margin:10px 0; }
#spambot {clear:both; font-size: 12px; margin:10px 0;}

<?php
}

// If from WPMU wp-signup check for hidden fields and kick an error instead of dieing.
function wpmu_check_hidden_fields() {

// Get values from POST data
$val0 = '';
$val1 = '';
$val2 = '';
if ( isset( $_POST['mathvalue0'] ) ) {
$val0 = $_POST['mathvalue0'];
}
if ( isset( $_POST['mathvalue1'] ) ) {
$val1 = $_POST['mathvalue1'];
}
if ( isset( $_POST['mathvalue2'] ) ) {
$val2 = $_POST['mathvalue2'];
}

// Check values
//if ( ( $val0 == '' ) || ( $val1 == '' ) || ( intval($val2) != (intval($val0) + intval($val1)) ) ) {
if ( ( $val0 == '' ) || ( $val1 == '' ) || ( intval($val2) != (intval($val0) – intval($val1)) ) ) {

$error = get_site_option('blockspam_error');
echo '’ . $error . ”;
exit;
}

}

function blockspam_site_admin_options_process() {
update_site_option( ‘blockspam_error’ , $_POST['blockspam_error'] );
}

function blockspam_site_admin_options() {
?>

<?php _e('spammers … get a life! ‘) ?>
<?php _e('You can really do better things in life.‘) ?>

The math request does appear on the registration page, but is not verified with the submitting, so basically you can leave it empty and Buddypress will give you a name anyway.
I will try to have a look how the Super-CAPTCHA plugin is doing it. But nowadays are captha’s easy to read by robots..
That’s why I like your more

Its works like a charm! Now my Buddypress site is powered with your preety plug-in