Scripts could not see control ToolkitScriptManager

Hi,

My server-side scripts and client-side scripts are unable to see the object ToolkitScriptManager ID="ScriptManager1".

Please see my code below:

Server-side:

if (this.Page.FindControl("ScriptManager1") != null)

{

((ScriptManager)this.Page.FindControl("ScriptManager1")).RegisterPostBackControl(btn);

}

Client-Side:

<asp:ToolkitScriptManagerID="ScriptManager1"runat="server"CombineScripts="false"EnablePartialRendering="true"LoadScriptsBeforeUI="true">

</asp:ToolkitScriptManager>

<asp:UpdatePanelID="UpdatePanel1"runat="server">

<ContentTemplate>

<asp:PanelID="Panel3"runat="server"Visible="false">

<asp:HiddenFieldID="HiddenField1"runat="server"/>

<asp:TabContainerID="TabContainer1"runat="server"CssClass="Tab"OnActiveTabChanged="TabContainer1_OnActiveTabChanged"AutoPostBack="true">

<asp:TabPanelrunat="server"ID="TabPanel1"HeaderText=" Page1 ">

<ContentTemplate>

<asp:PanelID="Panel4"runat="server"ScrollBars="Vertical"Height="500px">

<uc1:ucPageAID="ucPage1"runat="server"/>

</asp:Panel>

</ContentTemplate>

</asp:TabPanel>

<asp:TabPanelrunat="server"ID="TabPanel2"HeaderText="Page2"BackColor="#99CCFF">

<ContentTemplate>

<asp:PanelID="Panel5"runat="server"ScrollBars="Vertical"Height="500px">

<asp:HiddenFieldID="HiddenField3"runat="server"/>

<uc2:ucPageBID="ucPage2"runat="server"Visible="false"/>

</asp:Panel>

</ContentTemplate>

</asp:TabPanel>

<asp:TabPanelrunat="server"ID="TabPanel3"HeaderText="Page3">

<ContentTemplate>

<asp:PanelID="Panel6"runat="server"ScrollBars="Vertical"Height="500px">

<asp:HiddenFieldID="HiddenField4"runat="server"/>

<uc2:ucPage2ID="UcPage3"runat="server"Visible="false"/>

</asp:Panel>

</asp:TabContainer>

</asp:Panel>

</ContentTemplate>

</asp:UpdatePanel>

<scripttype="text/javascript">

Sys.Extended.UI.TabPanel.prototype._header_onclick =function(e) {

if (confirm("Yes?")) {

this.raiseClick();

this.get_owner().set_activeTab(this);}

};

</script>

In the server-side, the "FindControl" function is always returning null.

In the client-side, I always run into this error:  "Mircorsoft JScript runtime error: Sys.Extended.UI.TabPanel.prototype is null or not an object.  "  Research states to set the combinescripts property of the ajaxtoolkit to false, which I did.

Also, the line Sys.Extended.UI.TabPanel is all black on my page, unlike some the samples I've seen is blue.  Maybe this is a clue.

I'm using VS 2010, .Net Framework 4.5, AjaxControlToolkit.Binary.NET4.

Please advise.

Thanks,

tinac99