Redmine How to display application menu under specific top menu?

I am working on leave management system plugin so want to show application menu under lms menu.... here i past my init file code

 menu :top_menu, :leave_transactions, { :controller => 'dashboard', :action => 'index' }, :caption => 'LMS' , :if => Proc.new { User.current.logged? }
    menu :application_menu, :dashboard, { :controller => 'dashboard', :action => 'index' }, :caption => 'Dashboard' , :if => Proc.new { User.current.logged? }
    menu :application_menu, :leave_transactions, { :controller => 'leave_transactions', :action => 'index' }, :caption => 'Apply Leave' , :if => Proc.new { User.current.logged? }
    menu :application_menu, :holiday_informations, { :controller => 'holiday_informations', :action => 'index' }, :caption => 'Holiday' , :if => Proc.new { User.current.logged? }

Its working for me but application menu display all over menu. so i want to avoid this and when I click on lms menu that time application menu display..please help me