1) Changed ticket.date_approved from Date to DateTime. 2) Added inverse_of to has_many associations based on suggestion of rails_admin documentation: "If you set the :inverse_of option on your relations, RailsAdmin will automatically populate the inverse relationship in the modal creation window. (link next to :belongs_to and :has_many multiselect widgets) It will also hide the inverse relation on nested forms. As a good practice, you should always set :inverse_of options to all your associations, even if these are useless to ActiveRecord (in combination with :through and :as). RailsAdmin will take advantage of them."