Keypreview not previewing

[sjc]

Is there any reason why Keypreview on a form won't work ?

I have a real simple form (no text, sizable tool window, no control, min or max buttons, a combo box and that's pretty much it.)

Keypreview on the form is on and I have no key handling event handlers assigned to the combo box.
Typing in the combo box does not fire the keypreview event handler of the form.

I'm trying to stop the annoying beep when pressing enter in the combo box and I thought keypreview would do the trick.

Thanks for any help