setOutputMarkupPlaceholderTag(true) not working on modal window

[Warren Bell <Wa...@clarksnutrition.com>]

I have a button on a modal window. The button starts with isVisible set
to false. I get the following ajax error when I set it to true:
 
ERROR: Component with id [[okButton]] a was not found while trying to
perform markup update. Make sure you called
component.setOutputMarkupId(true) on the component whose markup you are
trying to update.
 
I am calling Component#setOutputMarkupId(true),
Component#setMarkupId(String id) and
Component#setOutputMarkupPlaceholderTag(true).
 
What do I need to do to make this work?
 
Thanks,
 
Warren