AJAX tab control postback of dropdown event in VB

I've read so many posts my head is spinning! So, I'm struggling w/ the autopost back of a dropdown from within a AJAX tab control.
Does anyone have a simple example? Here's my code.

<asp:ScriptManagerID="ScriptManager1"runat="server">
</asp:ScriptManager>
<asp:SqlDataSourceID="SqlEvents"runat="server"ConnectionString="<%$ ConnectionStrings:LLB_Con %>"
SelectCommand="SELECT [T], [X] FROM [Events] ORDER BY [startdate] desc"></asp:SqlDataSource>
<ajaxToolkit:TabContainerID="tabAdmin"runat="server"ActiveTabIndex="1"Height="512px"Width="1121px">
<ajaxToolkit:TabPanelID="TabPanel1"runat="server"HeaderText="Manage Data">
<ContentTemplate><br/>
<asp:HyperLinkID="hlEventFormat"runat="server"NavigateUrl="~/Admin/Event_Format.aspx"Text="Manage Event Format"/>
</ContentTemplate>
</ajaxToolkit:TabPanel>
<ajaxToolkit:TabPanelID="tpProcessing"runat="server"HeaderText="Event Processing">
<ContentTemplate><br/> <br/><br/>
<asp:DropDownListID="ddEvents"runat="server"
DataSourceID="SqlEvents"
DataTextField="T"
DataValueField="X"/><asp:HyperLinkID="hlEnter_Event"runat="server"Text="Enter Event Data"NavigateUrl="~/Admin/eventEntry.aspx"/>
</ContentTemplate>
</ajaxToolkit:TabPanel>
</ajaxToolkit:TabContainer>

I think you need to add at the DropDownList

AutoPostBack="True"

George