In addition to the link Vince mentioned: http://www.mojoportal.com/iiswebsetup.aspx which may help, make sure you actually have installed .NET 4 and configured your site with a .NET 4 application pool.

Best,

Joe

I see you are using ASP.NET 4.0 and I am sure you have it installed on your PC.

However, when I used Windows XP I always had to install the framework into IIS by running the following at the Command line from the folder of the version of the framework I wanted installed.

aspnet_regiis -i

This installs the chosen framework into IIS

Sometimes when I had problems I would have to re-install the framework to IIS again.

Also I have heard that ASP.NET 4.0 is not that IIS 5/6 friendly.  So if all else fails you may want to try installing mojoPortal  for Dot.Net 3.5

Rick

He means that you should be in the appropriate folder for the ASP.NET version you are installing. For instance, my .NET 4 installation is in:

C:\Windows\Microsoft.NET\Framework\v4.0.30319

So, I'd open a command prompt, them type "cd \Windows\Microsoft.NET\Framework\v4.0.30319" to get to the directory.

That's what you type into the command prompt window after navigating to the ASP.NET directory. It will (re)install the framework into IIS for you.