[flexcoders] itemRenderer null object error

[pdflibpilot]

I am so happy I was able to create an itemRenderer with an initialize
event that dynamically set the style for each item based on the source
data. This worked flawlessly for one HorizontalList ( List A) so I
tried to implement the same on a TileList (List B) on the same layout.
They have virtually the same dataProvider - List B items are
originally drag/dropped to List A.

These list are nearly identical in every way yet when the event fires
for the itemRenderer in List B it fails with "null object" error. It
seems that the data is not available when the event dispatches.  I am
at a loss as to why it works for one list and not the other. The data
used by the event is not null when it renders since all the items
(data) are accounted for.

here my itemRenderer code that works - 

<?xml version="1.0" encoding="utf-8"?>
<!-- itemRenderers\navScreenRender.mxml -->

<mx:Canvas xmlns:mx="http://www.adobe.com/2006/mxml"; 
        width="200" 
        height="200"
        horizontalScrollPolicy="off"
        verticalScrollPolicy="off"
        borderStyle="solid" backgroundImage="assets/images/{data.imageID}"
alpha="1.0" backgroundAlpha="1.0" borderColor="#333333">

<mx:Script>
<![CDATA[
                
private function setContentButton(event:Event,V):void{
                var e = event.currentTarget
                if(V==''){
                        e.styleName = 'customcontentbuttonOff'
                        e.alpha = 1.0
                        e.toolTip = "Content Editor is not enabled for this 
screen - click
to complete the setup"
                        }
                        else if(V!="(preset)"){
                                e.styleName = 'customcontentbuttonOn'
                                e.alpha = 1.0
                                e.toolTip = "Content Editor is enabled for this 
screen - click to
change the setup"
                        }
                        else if(V=="(preset)"){
                                e.alpha = 0.0
                        }
                }
                ]]>
                
</mx:Script>
        <mx:Text id="layoutLabel" text = "{data.label}"
                                fontSize="8"
                                color="#ffffff"
                                textAlign="center"
                                letterSpacing="0"
                                 horizontalCenter="0" verticalCenter="-38"/>
        <mx:Image   source = "assets/images/{data.imageID}" 
                                toolTip="{data.description}"
                                scaleContent="false" alpha="1" 
                                 visible="false"/>
        <mx:Button label="{data.displaySeq-0+1}" width="25" height="20"
cornerRadius="12" styleName="adminbutton" fontWeight="bold"
fontSize="9" verticalCenter="20" horizontalCenter="0"/>
        <mx:Button id="contentButton"
initialize="{setContentButton(event,data.contentLocation)}" 
                                label="C" width="18" height="18" 
                                cornerRadius="12" 
                                styleName="customcontentbuttonOff" 
                                fontWeight="bold" fontSize="10" 
                                verticalCenter="-1" horizontalCenter="0" 
                                alpha="1.0"/>
                                                
  </mx:Canvas>