Q:

Multiple UpdateProgress controls on a single page

I have a page with several UpdatePanel controls, each with a related UpdateProgress. When the asynchronous requests are posted back, only the first UpdateProgress control is displayed. The other requests complete successfully, but the UpdateProgress is not shown.
How can I get all the update panels on the page to show properly?
Here is a example that shows the problem (sorry it's a bit long):
aspx file:
<asp:ScriptManager ID="ScriptManager1" runat="server" />
<asp:UpdatePanel ID="UpdatePanel1" runat="server" UpdateMode="Conditional" ChildrenAsTriggers="true">
  <ContentTemplate>
    <asp:Timer ID="Timer1" runat="server" OnTick="Timer1_Tick" Enabled="true" Interval="1000" />
    <asp:Label ID="Label1" runat="server" />
  </ContentTemplate>
</asp:UpdatePanel>
<asp:UpdateProgress ID="UpdateProgress1" runat="server" AssociatedUpdatePanelID="UpdatePanel1">
  <ProgressTemplate>Updating...</ProgressTemplate>
</asp:UpdateProgress>
<asp:UpdatePanel ID="UpdatePanel2" runat="server" UpdateMode="Conditional" ChildrenAsTriggers="true">
  <ContentTemplate>
    <asp:Timer ID="Timer2" runat="server" OnTick="Timer2_Tick" Enabled="true" Interval="2000" />
    <asp:Label ID="Label2" runat="server" />
  </ContentTemplate>
</asp:UpdatePanel>
<asp:UpdateProgress ID="UpdateProgress2" runat="server" AssociatedUpdatePanelID="UpdatePanel2">
  <ProgressTemplate>Updating...</ProgressTemplate>
</asp:UpdateProgress>

codebehind:
protected void Timer1_Tick(object sender, EventArgs e) {
    System.Threading.Thread.Sleep(1000);
    Timer1.Enabled = false;
    Label1.Text = DateTime.Now.ToString("HH:mm:ss");
}

protected void Timer2_Tick(object sender, EventArgs e) {
    System.Threading.Thread.Sleep(1000);
    Timer2.Enabled = false;
    Label2.Text = DateTime.Now.ToString("HH:mm:ss");
}

A:

I just discovered that everything works as expected if I put the UpdateProgress before the corresponding UpdatePanel...
<asp:UpdateProgress ID="UpdateProgress1" runat="server" AssociatedUpdatePanelID="UpdatePanel1">
  <ProgressTemplate>Updating...</ProgressTemplate>
</asp:UpdateProgress>
<asp:UpdatePanel ID="UpdatePanel1" runat="server" UpdateMode="Conditional" ChildrenAsTriggers="true">
  <ContentTemplate>
    <asp:Timer ID="Timer1" runat="server" OnTick="Timer1_Tick" Enabled="true" Interval="1000" />
    <asp:Label ID="Label1" runat="server" />
  </ContentTemplate>
</asp:UpdatePanel>

