[flexcoders] item render inside grid passing param?

[flexcoderman]

when using a item renderer inside a data grid in flex 3
how do i pass a id inside the grid

example i have a grid column as

<mx:DataGridColumn headerText="ID" dataField="ID" id="ID" />


I have a button which throws an alert box up....

Alert.show(parentDocument.mygrid.ID);

but doesnt actually pull the id for the grid.                        
           

All im trying to do is pass the id to the httpservice im posting to.

anyone know of good examples on the net would be great