Index: extra/sample_plugin/app/models/meeting.rb
===================================================================
--- extra/sample_plugin/app/models/meeting.rb	(revision 22078)
+++ extra/sample_plugin/app/models/meeting.rb	(working copy)
@@ -7,6 +7,6 @@
                 :url => Proc.new {|o| {:controller => 'meetings', :action => 'show', :id => o.id}}
 
   acts_as_activity_provider :timestamp => 'scheduled_on',
-                            :scope => proc { includes(:project) },
+                            :scope => proc { joins(:project) },
                             :permission => nil
 end