Custom VirtualPathProvider not being used in IIS6

I added the following lines to Application_Start method in global.asax:

var provider = new TestVirtualPathProvider();
HostingEnvironment.RegisterVirtualPathProvider(provider);

Yet the 'TestVirtualPathProvider' is never used when deploying this application in IIS6 (it does in the ASP.NET Development Server).

Edit: the default path provider has always done its job correctly and served (non-embedded) views correctly. The problem is simply that I want to use my own path provider to provide embedded views. So, initially, I already had the following wildcard mapping configured:

Used wildcard mapping screenshot

Any possible reasons why this does not work in IIS6? Are there any other factors (handlers for example) wich might influence the used VirtualPathProvider?

Solution

For the combination Custom VPP + IIS6 + Precompiled site, we need to add the VPP from AppInitailize();

public static class AppStart
{
    public static void AppInitialize()
    {
    // code to be executed automatically by the framework
    }
}