Loaded SWF not displaying

Question

I've created a 'plugin' SWF file in CS3 using actionscript 3.
The purpose of this file is to be included as a postroll in the
open source flash media player JW FLV/Media Player (
http://www.jeroenwijering.com/?item=JW_Media_Player).
I have heavily customized the media player libraries to do
various new things/alter how things worked, and now want to be able
to include the SWF file within this into a child sprite/movie clip.
HOWEVER, the problem lies in that the media player is written
completely in AS2, and therefore I have to use the MovieClipLoader
class to load in the SWF. Updating the source to AS3 isn't an
option unfortunatly, and downgrading the AS3 SWF to AS2 isn't an
option either, mainly due to the fact I've learnt AS3, not AS2, and
find it frustrating trying to find the AS2 equivalent to the AS3
methods I know.
The problem though lies in that MovieClipLoader does not like
my SWF at all. Initially I was presented with a load of sandbox
errors from when it was loaded in, which I then resolved so that no
security errors are produced. However, whenever I load in the clip,
the target sprite/clip is empty. I have gone through checking that
no errors occur on load, and it reports that the loaded SWF has
been initialized, yet I see nothing. Also, the code loading the SWF
is not at fault as it loads any other SWF (even another AS3 SWF
which just creates a rectangle) no problem.
Oddly enough, using the MovieClip.loadMovie method works in
one situation - when you load it into the root of the AS2 file.
When loading it into an empty movie clip, the same problem of a
blank clip occurs. The problem is not specific to the media player
either, as it happened in any AS2 file where I was testing how to
load in the AS3 SWF.
If it is of any use, the sandbox errors produced by the AS3
file when loaded into AS2 swf I had to resolve where to do with
stage access for getting the stage height and width, and a
Loader.content error when pulling out the BitmapData. These were
resolved via setting the allowed domains policy and eliminating any
reference to stage.stageHeight/With.
Does anyone have any ideas on how to solve this? The only
possible solution I've been able to think of so far since the AS3
swf won't display is to play with the LocalConnection class as
tests showed I can communicate between the AS2 and AS3 files, but
this would have to be a last resort, and is less than ideal when
there can be multiple instances of the player running (I would need
to use unique connection names for each instance so as to prevent
player A interacting with player B, and also as only one of the
players can listen on the connection at once).

Answer 1

I have the component in the top level also,
I get this error:
TypeError: Error #2007: Parameter child must be non-null.
          at flash.display::DisplayObjectContainer/addChildAt()
          at fl.controls::BaseButton/drawBackground()[C:\Program Files (x86)\Adobe\Adobe Flash CS5\Common\Configuration\Component Source\ActionScript 3.0\User Interface\fl\controls\BaseButton.as:615]
          at fl.controls::LabelButton/draw()[C:\Program Files (x86)\Adobe\Adobe Flash CS5\Common\Configuration\Component Source\ActionScript 3.0\User Interface\fl\controls\LabelButton.as:724]
          at fl.core::UIComponent/drawNow()[C:\Program Files (x86)\Adobe\Adobe Flash CS5\Common\Configuration\Component Source\ActionScript 3.0\User Interface\fl\core\UIComponent.as:1343]
          at fl.controls::List/drawList()[C:\Program Files (x86)\Adobe\Adobe Flash CS5\Common\Configuration\Component Source\ActionScript 3.0\User Interface\fl\controls\List.as:594]
          at fl.controls::List/draw()[C:\Program Files (x86)\Adobe\Adobe Flash CS5\Common\Configuration\Component Source\ActionScript 3.0\User Interface\fl\controls\List.as:474]
          at .tree::TreeList/draw()
          at fl.core::UIComponent/callLaterDispatcher()[C:\Program Files (x86)\Adobe\Adobe Flash CS5\Common\Configuration\Component Source\ActionScript 3.0\User Interface\fl\core\UIComponent.as:1532]
I've checked the definitions for the tree component,
The LabelButton and List I don't have much control over.
I'm not sure how to fix this.  The xml is correct and loads easily if it's in the root document.
The list component doesn't load the labels, It stops on the first one.
  What do I do next?