Commented Unassigned: ASP.NET Ajax Client Side Framework failed to load. [27694]

Hi
I am using ASP.NET 4.0 for my web application. I have used AjaxControlTool kit for using ModalPopup control. It runs fine in my development machine. But when i deploy in production environment i am getting two javascript error messages which are stoping the page functionality altogether.

1) ASP.NET AJAX Client Side framework failed to load.
2) 'Sys' is undefined.

I have tried with the below solutions but none worked.

a) Tried re-installing the framework 4 in my prod server.
b) Tried with new version of AjaxControlTool Kit(4.1).

Could you please help me to solve this issue at the earliest.
Comments: @ganyrocks Thanks! In my case the .axd extension was configured. Adding the following to web.config file worked. <httpModules> <add name="ScriptModule" type="System.Web.Handlers.ScriptModule, System.Web.Extensions, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/> </httpModules> <httpHandlers> <remove verb="*" path="*.asmx"/> <add verb="*" path="*.asmx" validate="false" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/> <add verb="*" path="*_AppService.axd" validate="false" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/> <add verb="GET,HEAD" path="ScriptResource.axd" type="System.Web.Handlers.ScriptResourceHandler, System.Web.Extensions, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" validate="false"/> </httpHandlers>