dataTipFunction for linechart

[exclosion]

I have the code below as my dataTipFunction for my line chart. But currently now, it only displays the yValue which is my data for revenue. So how can I get it to display the xValue which is the name from my data? Also, the revenue now are just display as number alone, can I include something like
"Revenue: ..."? thanks:)

private function theDataTipFunction(hitData:HitData):String
{
var s:String;
s = hitData.item.name;
s += LineSeriesItem(hitData.chartItem).yValue ;

return s;
}