Widgets not available

I just installed this plugin ( WP 3.2.1, BP 1.5rc1) and I can't see the widget options on the Appearance -> Widgets page. I've deactivated and re-activated the plugin, turned on debug mode in WP to look for errors etc. but they just don't appear.

I saw the other thread where the OP mentioned network-activating, but I'm not running in MultiSite mode.

Any thoughts?