ActionScript 3.0 :: Loaded Movie Calls Function In Main Interface?

I have an interface that contains audio controls in the Library (class: AudioControls)When a movie is loaded into the interface, and it happens to contain a sound (class: Audio_1), this loaded movie calls an interface function to show the audio controls:

Code:
if (Interface._ui != null) {
Interface._ui.playCurrentAudio();
}

The problem is, the playCurrentAudio() func in the interface contains some code that refers to nested MCs:

Code:
public function showAudioControls():void {
audioControls.x = 710;
audioControls.y = 583;
//

[code]....

That would be the speaker, rewind_btn, playPause_btn, etc. Referring to the parent clip, "audioControls", is no problem of course. But I get an error when I publish the loaded movie:

1119: Access of possibly undefined property speaker through a reference with static type AudioControls.
1119: Access of possibly undefined property rewind_btn through a reference with static type AudioControls.
1119: Access of possibly undefined property playPause_btn through a reference with static type AudioControls.