Local connection and event propogation

I dont seem to be having much luck with LC…

I generally use a holder MC for a set of buttons with a listener assigned to the holder and let Flash detect the child MCs in a mouse event

buttonHolder.addEventListener(MouseEvent.CLICK, Clicked, false, 0, true);

private function Clicked(event:MouseEvent):void
   var icName:String = event.target.name;
   this[icName]();  // calls a method for the button

I have two SWFs in a HTML page. One SWF is a set of buttons that control the animation in the other SWF through LocalConnection. In Firefox everything seems OK.
However, in IE where the Flash Debugger is present, errors are thrown, even though the Local Connection works:

Error #2044: Unhandled AsyncErrorEvent:. text=Error #2095: flash.net.LocalConnection was unable to invoke callback BarButtons. error=ArgumentError: Error #2025: The supplied DisplayObject must be a child of the caller.

As a test I recoded one of the buttons to have its own event listener and the errors no longer occur.

What is happening here?