diff --git a/actionpack/lib/action_view/helpers/scriptaculous_helper.rb b/actionpack/lib/action_view/helpers/scriptaculous_helper.rb
index 263be5d0324f860e57f4ec6e683e120bfa7c2328..2c416b0026ed5e1b48c753cd09e60254e9097556 100644
--- a/actionpack/lib/action_view/helpers/scriptaculous_helper.rb
+++ b/actionpack/lib/action_view/helpers/scriptaculous_helper.rb
@@ -69,6 +69,11 @@ def visual_effect(name, element_id = false, js_options = {})
       # containing the values of the ids of elements the sortable consists 
       # of, in the current order.
       #
+      # Important: For this to work, the sortable elements must have id
+      # attributes in the form "string_identifier". For example, "item_1". Only
+      # the identifier part of the id attribute will be serialized.
+      #
+      #
       # You can change the behaviour with various options, see
       # http://script.aculo.us for more documentation.
       def sortable_element(element_id, options = {})