REMOVED_FROM_STAGE loaded swf + removeChild routines

I have a .swf file being loaded with a very large amount of internal objects/childs/loaded-contents.

Been preparing a general cleanup method removing listeners, timers, tweens, children, sound, netstreams and so on.

When i run the cleanup function with a simple internal button, all is performed perfectly.

But as soon as I load the .swf and unload it in a container .fla, then the REMOVED_FROM_STAGE which calls stopall() function doing the cleanup (in 2 steps), I get error

 
Error: Error #2069: The Loader class does not implement this method.
 at Error$/throwError()
 at flash.display::Loader/removeChildAt()
 at classes::presentor/checkifchildren()
 at classes::presentor/checkifchildren()
 at classes::presentor/checkifchildren()
 at classes::presentor/checkifchildren()
 at classes::presentor/checkifchildren()
 at classes::presentor/checkifchildren()
 at classes::presentor/checkifchildren()
 at classes::presentor/checkifchildren()
 at classes::presentor/removeallremainingchildren()
 at classes::presentor/cleanrest()
 at classes::presentor/stopall()
 at flash.display::DisplayObjectContainer/removeChild()
 at load_fla::MainTimeline/rem()
 at load_fla::MainTimeline/remove()

basically It looks like the Loader class is not allowed to perform the second cleanup part which removes all the child objects.

Why?

And also another minor detail, seems like URLLoader (loader which loads a CSS file) is not allowed to unload with line

 
loader.unload();

another weird thing.

So, anybody knows what I’m missing?