FormView KeepInEditMode=true isn't retaining values

Question

I have an "Edit Page" in my application. It uses a FormView bound to an EntityDataSource.

I have a handler setup for the FormView OnItemUpdating event. If an exception occurs, I set the "KeepInEditMode=true". This should retain the user entered values on all of the text boxes instead of rebinding the FormView to the data again. (Right?)

Well, it isn't working...

I have stepped through the code via the debugger and the "KeepInEditMode" does get set to true, but as soon as the page reloads, the values revert back to the original database values (the data is being rebound).

I should also mention that I am setting "ExceptionHandled" to true. I am doing this because I am handling the Exception by displaying an error in a specific area of the page and if I dont mark it as handled, IE generates an Exception popup.

Any ideas?