Cannot select text via TLF API by using SelectionManager "selectRange" method

I am on Flex 4.0.13654 SDK from Jan 20 2010.

The following 50 lines of code illustrate 4 different methods to select text, including

1)  calling "selectAll" method on s:TextInput component creation,

2)  calling "selectRange" method on SelectionManager

3) applying instance of SelectionState to SelectionManager

4) calling "selectAll" method on SelectionManager

all failed

<?xml version="1.0" encoding="utf-8"?>
<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009" 
               xmlns:s="library://ns.adobe.com/flex/spark" 
               xmlns:mx="library://ns.adobe.com/flex/halo" 
               minWidth="1024" minHeight="768">

    <fx:Script>
        <![CDATA[
            import flashx.textLayout.edit.EditManager;
            import flashx.textLayout.edit.SelectionManager;
            import flashx.textLayout.edit.SelectionState;
            import flashx.textLayout.elements.TextRange;
            import flashx.textLayout.events.SelectionEvent;
            import flashx.textLayout.formats.ITextLayoutFormat;
            import flashx.textLayout.formats.TextLayoutFormat;
            import flashx.textLayout.operations.ApplyFormatOperation;
            import flashx.undo.UndoManager;
            
            protected function button1_clickHandler(event:MouseEvent):void
            {
                rt.textFlow.interactionManager = new SelectionManager();
                rt.textFlow.addEventListener(SelectionEvent.SELECTION_CHANGE, setSelectionRange);
                                                
                rt.textFlow.interactionManager.selectRange(0, 2);                
                rt.textFlow.interactionManager.refreshSelection();
                
                
                rt2.textFlow.interactionManager = new SelectionManager();
                rt2.textFlow.addEventListener(SelectionEvent.SELECTION_CHANGE, setSelectionRange);
                
                var format:TextLayoutFormat = new TextLayoutFormat();
                format.backgroundColor      = 0xFF99CC;
                format.color                = 0x000000;          
                                
                var currentSelectionState : SelectionState = new SelectionState(rt2.textFlow, 0, 2, format);                
                rt2.textFlow.interactionManager.setSelectionState(currentSelectionState);                
                rt2.textFlow.interactionManager.refreshSelection();                                 
                
                ret.textFlow.interactionManager = new EditManager(new UndoManager());
                ret.textFlow.addEventListener(SelectionEvent.SELECTION_CHANGE, setSelectionRange);
                ret.textFlow.interactionManager.selectAll();                                
            }
            
            private function setSelectionRange(event:SelectionEvent):void
            {
                trace ("trace setSelectionRange", event.target.toString());                
            }                        
            
        ]]>
    </fx:Script>

    <fx:Declarations>
        <!-- Place non-visual elements (e.g., services, value objects) here -->
    </fx:Declarations>    
    <s:Group left="100" top="100">
        <s:layout>
            <s:HorizontalLayout>
                
            </s:HorizontalLayout>
        </s:layout>
        
        <s:TextInput id="ti" 
                     text="Sample text-1" 
                     creationComplete="ti.selectAll();"/>
        
        <s:RichText id="rt" text="Sample text-2">
            
        </s:RichText>
        
        <s:RichText id="rt2" text="Sample text-3">
            
        </s:RichText>
        <s:RichEditableText id="ret" text="Sample text-4">
            
        </s:RichEditableText>
        <s:Button label="Apply" click="button1_clickHandler(event)">
            
        </s:Button>
    </s:Group>
</s:Application>