Error In AjaxToolKit

Hi

I have just installed the nopcommerce version 1.5 and when I try to click on the New Product-> product. it shows me the following error.  

Type 'AjaxControlToolkit.ToolkitScriptManager' does not have a public property named 'CompositeScript-ScriptMode'.

There is any other solution without installing .net 3.5 sp1

thanks

rajeshdhiman wrote:
•ASP.NET 3.5 SP1 is a system requirement for nopcommerce

I have already installed 3.5 service pack 1. but still i m getting same error.

Please somebody help me???