Attach to process….doesn’t work

In one of my customer's VS.NET solutions, we use IIS to host a .NET Remoting object. Somehow, VS.NET fails to attach to IIS when we debug our client application (which in this case is a Windows Forms application). Luckely, James Avery's Visual Studio Hacks pointed me at a macro that allows us to attach to the ASP.NET worker process (e.g. through a keyboard shortcut). However, for me, it doesn't work. At first I got a warning that that process does not contain unmanaged code. But successive attempts did not provide any warning at all....