Microsoft JScript runtime error: AjaxControlToolkit requires ASP.NET Ajax 4.0 scripts

AjaxControlToolkit requires ASP.NET Ajax 4.0 scripts. Ensure the correct version of the scripts are referenced. If you are using an ASP.

changed this

<asp:scriptmanager id="ScriptManager1" runat="server"></asp:scriptmanager>

to this

<cc1:ToolkitScriptManager ID="ToolkitScriptManager1" runat="server">cc1:ToolkitScriptManager>

Problem solved.