How to see OldValue/NewValue collections with FormView?

[Guest]

I want to be able to see the changes a user makes while in the Edit Mode of
FormView.

My understanding is that in the FormView ItemUpdating event, I should be
able to get a collection of Keys, OldValues, and NewValues. Here's the
sequence. . .
1. My Objectdatasource is populated & bound to FormView
2. The FormView displays properly for all
modes(ItemTemplate/EditTemplate/InsertTemplate)
3. I change some values while in Edit Mode
4. I submit the change via a Button that calls FormView ItemUpdate Command
5. The ItemUpdating event fires
6. The keys collection is populated with the DataKeyNames. The NewValues
and OldValues collection are empty.
(They are also empty in the ItemUpdated event)

I need the old & new values to see what has changed. Anyone have any ideas
on why they are empty?