BuddyPress.org

Was this plugin working before and now it is not? If so, what has changed since then? Did you upgrade WPMU?

What versions of WP/MU and BuddyPress are you running?

If you look at the WP Plugin Repository for this plugin, others are having issues with it as well. I would suggest contacting the developer of the plugin and ask when they plan on updating it for the current versions of WP and BP.