[flexcoders] new to VO's, why won't this cast?

[Derrick Anderson]

hi, i am trying to incorporate value objects into my programming- i have a
very simple one set up

[Bindable]
    public class EmployeeVO
    {
        public var employeeID:uint;
        public var roleID:Number;
        public var employeeTypeID:Number;
        public var employeeStatusID:Number;

and i'm trying to cast a datagrid item which contains these 4 values onclick
like:

var testVO:EmployeeVO = DataGrid(event.currentTarget).selectedItem as
EmployeeVO;

testVO is always null, and I can't figure out why.  the selectedItem
properties are (as they are seen in debugger):

employeeID = 1830 [0x726]
employeeStatusID = 2
employeeTypeID = 1
mx_internal_uid = "D3C...."
roleID = 3

can anyone see what i'm doing wrong here?

tia.
d.