[flexcoders] Progress Bar Item Renderer

[triggersoftware]

I'm trying to create a progress bar item renderer, but I can't get the
value of progress bar to bind:

<mx:AdvancedDataGridColumn headerText="% Complete" width="100"> 
        <mx:itemRenderer>
                <mx:Component>
                        <mx:VBox>                                               
                
                                <mx:Label id="lbl" 
text="{data.percentageComplete}"/>
                                <mx:ProgressBar label="%3%%" maximum="100" 
width="100%"
mode="manual" source="{data.percentageComplete}"/>                              
                                        
                        </mx:VBox>
                </mx:Component>
        </mx:itemRenderer>
</mx:AdvancedDataGridColumn>                            

You don't appear to be able to bind the value using source.  What am I
doing wrong?