User Control Page Load not firing (nor event handlers) in VS 2005

[Dood]

I have a page that has a tab control which toggles which user control
is loaded into a placeholder. The user controls that are loaded into
this place holder have other user controls in them, making 3 levels.
When I select a drop down list that is in the 3rd level user control,
it causes a post back, but only the postback event on the main page
(1st level) fires, nothing else happens in any of the user controls in
the 2nd and 3rd level. Any help would be nice! (PS - this code worked
in 2003, but have since converted to 2005).

Dood

 

[Dood]

More info: The main page (1st level) loads the user control
programatically into the placeholder, is there something special that
needs to be done in order for the pageload events/postback event
handlers in the loaded user control to fire?