fix small authorization

app/controllers/admin/tickets_controller.rb

@@ -18,6 +18,7 @@ class Admin::TicketsController < OrbitAdminController
         end
   		else
         @categories = authorizations.collect{|authorization| authorization.category}
+        @categories.delete(nil)
         @categories.each do |category|
           temp = Ticket.where(:category_id => category.id).open.not_urgent.limit(5).asc(:created_at)
           @tickets[category] = temp if temp.count > 0