datetime

app/admin/bans.rb

@@ -21,8 +21,8 @@ ActiveAdmin.register Ban do
       f.input :frequency, :as => :select, :member_label => :name  # https://github.com/justinfrench/formtastic/blob/master/lib/formtastic/inputs/select_input.rb
       f.input :hostmask
       f.input :reason
-      f.input :valid_from, :as => :datetime
-      f.input :valid_to, :as => :datetime
+      f.input :valid_from
+      f.input :valid_to
       f.input :activate
     end
     f.buttons