Telerik RadGrid Hierarchical - Child table not displaying

Trying to follow along an article to create a hierarchical grid using Telerik RadGrid.

http://www.telerik.com/help/aspnet-ajax/grid-hierarchy-tutorial.html

I found when I run my page the detail table does not show. I don't get any errors though. Anyone know why?

Here is the relevant code I believe:
....

    <telerik:RadScriptManager ID="RadScriptManager1" runat="server">
    </telerik:RadScriptManager>
    <telerik:RadAjaxManager ID="RadAjaxManager1" runat="server">
        <AjaxSettings>
            <telerik:AjaxSetting AjaxControlID="RadGridMyParent">
                <UpdatedControls>
                    <telerik:AjaxUpdatedControl ControlID="RadGridMyParent" />
                </UpdatedControls>
            </telerik:AjaxSetting>
        </AjaxSettings>
    </telerik:RadAjaxManager>


    <telerik:RadGrid ID="RadGridMyParent" runat="server" CellSpacing="0"
        DataSourceID="SQLDataSourceParent" GridLines="None" Skin="Metro"> <MasterTableView AllowPaging="True" AutoGenerateColumns="False" DataKeyNames="SampleNo"
            DataSourceID="SQLDataSourceParent">
    <DetailTables>
        <telerik:GridTableView runat="server" DataKeyNames="SampleNo"
            DataSourceID="SqlDataSourceAnalysis">



...blah...blah...

    <asp:SqlDataSource ID="SQLDataSourceParent" runat="server"
        ConnectionString="<%$ ConnectionStrings:XConnectionString %>"
        SelectCommand="SELECT * FROM [MyParent] ORDER BY [Autonumber]">
    </asp:SqlDataSource>

    <asp:SqlDataSource ID="SqlDataSourceAnalysis" runat="server"
        ConnectionString="<%$ ConnectionStrings:XConnectionString %>"
        SelectCommand="SELECT * FROM [MySub] WHERE ([SampleNo] = @SampleNo)">
        <SelectParameters>
            <asp:Parameter Name="SampleNo" Type="String" />
        </SelectParameters>
    </asp:SqlDataSource>

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