Problem after hosting the Asp.Net website on IIS of Windows Server 2003

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C#2.0

C#

Good Evening Friends,
I have hosted a website on IIS of my local machine and its working fine on every PC in LAN but when I am trying to host the same website on Windows Server 2003 it is giving me compile time error that is :-

Unrecognized attribute 'type'.

<configsections>
<sectiongroup name="system.web.extensions" type="System.Web.Configuration.SystemWebExtensionsSectionGroup, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35">
<sectiongroup name="scripting" type="System.Web.Configuration.ScriptingSectionGroup, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35">

So I think the issue is with version
I have Developed website on framework 2.0 in visual Studio 2005 .
I Google the issue the solution I am getting is to change the ISS version but I am not getting how to change the Version in ISS .
Please Help . Every Little help will be appreciated.
Thanks In Advance.