Could not load file or assembly 'Microsoft.Web.Extensions'

I copied my ASP.NET 2.0 website source code to another machine. After making required settings (creating virtual directory, allocating folder permissions, etc), I found following error while running the project.

Could not load file or assembly 'System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The system cannot find the file specified.

Everything on the new machine was same as old machine, such as:

• .Net Framework
• Visual Studio
• ASP.NET 2.0 AJAX Extension.

(All things were in place with all the AJAX assemblies)

Following files were there in "C:\Program Files\Microsoft ASP.NET\ASP.NET 2.0 AJAX Extensions\v1.0.61025".

• AJAXExtensionsToolbox.dll
• System.Web.Extensions.Design.dll
• System.Web.Extensions.dll

Where's the problem ..........?

I googled and found a following fix that PublicTokenKey should be in AllCaps

Bad : PublicKeyToken=31bf3856ad364e35
Good : PublicKeyToken=31BF3856AD364E35

Still the problem remained same ..........!

Suddenly I noticed that on old machine the source code was placed in C: Drive and on new machine I copied it to D: drive.

Now I Knew why it was unable to find the specified assembly.

So I simply copied the System.Web.Extensions.dll in the bin directory and every thing worked fine.