I have been trying for 2 days now to get my Kentico 6.0.27 (SP1) installation set up to show a custom error page.

The site is running on Windows Server 2008 R2 Standard, IIS 7.5, .NET 4.0 - and it's running in a virtual directory underneath another site.

I have followed the instructions here: http://devnet.kentico.com/docs/devguide/index.html?configuring_custom_error_pages.htm

(Although it's not clear from that page if you have to do both of the things described, I've tried them both, individually as well as at the same time.)

I've been playing Tech Support Ping Pong with an assortment of techs, not one of whom has been able to help - and some of whom have contradicted others.

At the suggestion of tech support, I've tried what's described here, even though I'm NOT using custom URL extensions or extensionless URLs: http://devnet.kentico.com/docs/devguide/index.html?custom_url_extensions_iis7.htm

Is there something special about setting up custom error pages when you're running a site in a virtual directory?

It is positively ludicrous to have to spend this much time on something that's supposed to be straightforward.

Hoping someone here has had the same problem and solved it.