My code-behind function is below.

1    Protected Sub tx_taserDeputy_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles tx_taserDeputy.SelectedIndexChanged
2            Session("taserDeputy") = tx_taserDeputy.SelectedItem.Value
3    
4        End Sub
 

  Here is my dropdownlist

1    <asp:DropDownList ID="tx_taserDeputy" runat="server" DataSourceID="DSesocad"
2                                          DataTextField="NAME" DataValueField="NAME" Font-Names="Verdana" Font-Size="8pt" AppendDataBoundItems="True">
3                                          <asp:ListItem Selected="True"></asp:ListItem>
4                                      </asp:DropDownList>

Obviously I have a dropdownlist that is supposed to fire the above selectedindexchanged function.  I have a popup window that is another aspx 
page that checks to see if the session variable in the selectedindexchanged function is set properly.

This is not working.  Any ideas what my be wrong?

No PostBack?

AutoPostBack="True"

You have to add
AutoPostBack="True"

And you can put the dropdownlist in a UpdatePanel of ajax so you don't feel that the page
postback every time you choose another item at the dropdownlist

note:UpdatePanel need a ScriptManger.

I have added the updatepanel to the page and have nested the dropdownlist within it.  I turned autopostback = true.

I have this in page load:

dropdownlist1.Attributes.Add("OnSelectedIndexChanged", "javascript:test();")

the js function test will run when the selectedindex of the drop down is changed.  I understand that with the updatepanel I don't have to worry about the whole page posting back but for some reason my test function is not firing.  The test funtion is this: