App_Code not accessible when not in wwwroot dir

Hi
I have to move some web sites from a server 2003 IIS 6 to a new Server2012 IIS 8.

Unfortunately the website throws an error when trying to access the App_Code dir on the new server.

The websites are not stored in the wwwroot directory.
The Location is: D:\webs\website1
App_code dir location is D:\webs\website1\App_Code

Each website has it's own App_Code folder

When I move the content of the App_Code folder to C:\inetpub\wwwroot\App_Code it's working
But this is no option, because I have many websites which use all own App_Code folders.

Is there a way to force/enable IIS to use App_Code folder outside wwwwroot?

This worked on my old server perfectly and I have no idea how to make it work on the new server.