sorting on date column not working

[sipra]

Hey,
I have date column in a datagrid,and the format is Feb 12.i have used dateCompare fuction in the sorting time.And also used the dateformatter.But not sorting my date column.

private function date_sortCompareFunc(itemA:Object, itemB:Object):int {
if(itemA.transac_date!=''){
var date1:String = itemA.transac_date + ', 2009';
var date2:String = itemB.transac_date + ', 2009';
}
else
{
date1 = itemA.transac_date;
date2 = itemB.transac_date;
}

var dateN:String = dateFormatter.format(date1);
var dateM:String = dateFormatter.format(date2);
var dateA:Date = new Date(Date.parse(dateN));
var dateB:Date = new Date(Date.parse(dateM));
return ObjectUtil.dateCompare(dateA, dateB);
}

I have used this function in sortCompareFunction.Please help.
Thanks in advance.