ransack sort_link in association

i tried using sort_link in my table head, but it's not work, is there something that I missed?

this is my action

def user_admin
    params[:q] ||= {}
    @search = Spree::User.includes(:spree_roles).where('spree_roles.name' => ["admin", "finance", "operator", "marketing"]).ransack(params[:q])
    @users = @search.result.page(params[:page]).per(Spree::Config[:admin_products_per_page])
end

and this is the table head

<th><%= sort_link @search, :spree_roles_name , Spree.t('role') %></th>