Flex :: Dynamically Creating Datagrid And Its Columns?

1) Using datefield as item renderer in flex.I am dynamically creating datagrid and its columns. like

dataGridColumn=new DataGridColumn();
dataGridColumn.dataField="invoiceDTO.invoiceDate";// I read this value from XML
dataGridColumn.editorDataField="selectedDate";
dataGridColumn.itemRenderer=new ClassFactory(DateFieldRenderer);
dataGridColumn.rendererIsEditor=true;

But when UI is generated i get the error invoiceDTO.invoiceDate not found on the TestDTO

//Test DTO

public class TestDTO
{
public var invoiceDTO:InvoiceDTO;
}

My objective is my dataField should be binded with datafield inside the datagrid.How can i do it in actionscript

2) I need to present combobox as item renderer. (same like case 1). But how can i assign dataprovider in the combobox which is present inside the datagrid.