Index xml target.name.length and double-digits issue

I have an issue, I have about 25 mc’s that are named carBtn1 through carBtn25 - the problem is when I index my array - its only taking the first number from the end of the carBtn, so carBtn1 is seen as the same as carBtn10. I tried taking the last 2 digits off which works for 2 digit numbers - but everything below 10 isnt working anymore. Im not sure what to do to get it working…

Here is my code:

// variables
var popInfo:popMc;


// load xml
var xml:XML = new XML();
var loader:URLLoader = new URLLoader();
loader.load(new URLRequest("data/cities.xml"));
loader.addEventListener(Event.COMPLETE,
    function(evt:Event):void {
        xml = XML(evt.target.data);
        //trace(xml.city[0][email protected]());
        var url:URLRequest = new URLRequest(xml.city[0][email protected]()); 

    }
);

// event listeners
stage.addEventListener(MouseEvent.CLICK, onClickStageRemove);

for (var j:int = 0; j < 11; j++)
{
getChildByName("carBtn" + j).addEventListener(MouseEvent.CLICK, onClickLoadData);
getChildByName("carBtn" + j).addEventListener(MouseEvent.MOUSE_OVER, onCarHover);
getChildByName("carBtn" + j).addEventListener(MouseEvent.MOUSE_OUT, onCarOut);
}



// button mode
buttonMode = true;

// functions
function onCarHover(event:MouseEvent):void
{
    event.target.gotoAndPlay(11);
    
}

function onCarOut(event:MouseEvent):void
{
    event.target.gotoAndPlay(10);
}


function onClickLoadData(event:MouseEvent):void
{
    popInfo = new popMc();
    popInfo.x = 100;
    popInfo.y = 50;
    addChild(popInfo);    
    popInfo.closeBtn.addEventListener(MouseEvent.CLICK , onClickRemove);
    popInfo.nyopBtn.addEventListener(MouseEvent.CLICK, onClickNYOP);
    //better approach would be add separate classFile to haldle some popInfo's events
    //such removing on stageClick in that file u could add those functions:
    var index:Number=event.target.name.slice(event.target.name.length-1);
    popInfo.carsizeText.text = xml.city[index].bidlist.carsize.descendants().toXMLString();
    popInfo.priceText.text = xml.city[index].bidlist.price.descendants().toXMLString();
    popInfo.savingsText.text = xml.city[index].bidlist.savings.descendants().toXMLString();
    popInfo.stateText.text = xml.city[index][email protected]();   
    addChild(popInfo);    
}

    
function onClickRemove(event:MouseEvent):void
{
    popInfo.closeBtn.removeEventListener(MouseEvent.CLICK, onClickRemove);
    popInfo.nyopBtn.removeEventListener(MouseEvent.CLICK, onClickNYOP);
    removeChild(popInfo);
}

function onClickStageRemove(event:MouseEvent):void
{
    if(event.eventPhase == EventPhase.AT_TARGET) {
        removeChild(popInfo);
    }
}

function onClickNYOP(event:MouseEvent):void 
{
    //navigateToURL(url, "_blank");
    // navigateToURL(urlNY, "_blank"); //trying to get this variable to work
    ExternalInterface.call("selectNY");

}

// set button mode here