ListBox Inside DataList Control Always Giving the Text of the First Item

Question

I have a ListBox inside DataList control. The Autopostback is set to true in the ListBox.

For some reason when I select an item from the ListBox control and I check in the ListBox_SelectionChanged event it is always the First item of the ListBox items. Why is that?

I just checked and the SelectedIndex is set to 0 even if I select the 5th or 6th item in the ListBox.

           >
      <ItemTemplate>
      <div style="background-color:#FFCC99; border:2px solid black; padding:2px">
     <div style="background-color:lightgreen; border:2px solid black; padding:2px">
      <%# Eval("NounTypeName") %>
      </div>

       <asp:ListBox ID="lbNounTypes" AutoPostBack="true" DataTextField="Key" DataValueField="NounTypeId" SelectionMode="Single"  
              DataSource='<%# Eval("Attributes") %>' runat="server" 
              onselectedindexchanged="lbNounTypes_SelectedIndexChanged">

       </asp:ListBox>

 protected void lbNounTypes_SelectedIndexChanged(object sender, EventArgs e)
        {
            var lb = sender as ListBox;

            // lb.SelectedIndex is also 0

I think I may have found the problem. The ListBox DataValueField is same for a ListBox and the SelectedItem is returned based on the selection of the value.