Dropdownlist .Value = .Text - why?

If I Databind a dropdownlist to a ListItemCollection that contains ListItems the ListItem.Value isn't being returned when I check SelectedItem??

 1 With uxAllSizes
2
3 .Items.Clear()
4
5 Dim SizesDisplay As New ListItemCollection
6
7 For Each Size As DataRow In dtSizes.Rows
8
9 Dim aSize As New System.Web.UI.WebControls.ListItem
10 aSize.Value = Size("SizeID")
11
12 ...