Got it. We don't think Cassini passes the requests to ASP.NET if the folder is not found. We are pretty sure it's a 404 situation, but we'd need to create a test app to verify it for sure. We probably won't be able to get to it until next week as we are stressed over regressing last additions to the next release of Cassini (it's two weeks overdue now) - we are sorry for the delay. Please post again here on Monday, if don't mind, if you still need the answer then.
Best regards,
UltiDev Team.
Please donate at
http://www.ultidev.com/products/Donate.aspx to help us improve our products.