Refresh Parent Nested Update Panel using Javascript

Well it sounds complicated but here it goes. I have a Page which includes:

javascript function :

function myfunc() {alert('ready'); <%=ClientScript.GetPostBackEventReference(Panel2, "")%>; }

Panel1 { contains Panel2 }

Panel3 { contains iframe1}

i call from a button in iframe1: Page.ClientScript.RegisterClientScriptBlock(this.GetType(), "script", "parent.myfunc();", true);

The above line works correctly and i see the alert 'ready'. But the panel does not refresh!

The panel code:

<ajaxToolkit:ToolkitScriptManager ID="MyToolkitScriptManager" runat="server" EnablePartialRendering="true" /><asp:UpdatePanel ID="Panel1" runat="server" UpdateMode="Conditional" ChildrenAsTriggers="false">
     ...<asp:UpdatePanel ID="Panel2" runat="server" UpdateMode="Conditional">
           ...</asp:UpdatePanel>
     ...</asp:UpdatePanel><asp:UpdatePanel ID="Panel3" runat="server" UpdateMode="Conditional"><ContentTemplate><iframe id="iframe1" runat="server" enableviewstate="true" src="xxx.aspx" /></ContentTemplate></asp:UpdatePanel>

Any idea why Panel2 does not refresh? Thanks