Use of undefined constant BP_VERSION

When plugin is activated, then the following alert is displayed:

The plugin generated 550 characters of unexpected output during activation. If you notice “headers already sent” messages, problems with syndication feeds or other issues, try deactivating or removing this plugin.

Voila… if it can help you

I ‘ve checked this file around line 117 but I’m newbie ?? I don’t know how to update it

//if is not bp 1.5
if (  version_compare( BP_VERSION, '1.5' ) < 0 )
	add_action( 'wp', 'bp_notifications_manager_subnav');
else
	add_action( 'bp_setup_nav', 'bp_notifications_manager_subnav' );