Problem with Cannot add duplicate collection entry of type 'add' with unique key attribute 'name' set to 'ScriptHandlerFactory'

Hi, my name is Arif,

I've tried to deploy the website in windows server 2008 (IIS 7.0). However, it does not work successfully. I developed the website using windows xp and I also have tried to published in windows xp and it works great.

For that projects, I use AJAX. in windows server 2008(IIS 7.0) I am sure that I have installed ajax extension which is the same version that i have installed in my local machine ( windows xp).

Here is the error details that I've got, any idea how to solve this error?

142:
  143:         <add name="ScriptHandlerFactory" verb="*" path="*.asmx" preCondition="integratedMode"
  144:              type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/>