>I agree that it sounds as if you are referencing the correct class/assembly in web.config.
>But I don't know why the redirect didn't work (or, come to that, why the default validator was called)
>The implication is that although properly referenced your class is not in fact being used.
>Are you sure the page in question is within the relevant web.config scope?
>Is your IsValidRequestString method calling the base class implementation ?
>First step is to establish for sure whether your method is being called (either via debug or event logging?)
>FWIW I just tested using the sample class I posted earlier and that worked as expected so the principle is correct.....

When I change the Web.Config, I can see that it takes a little bit longer for that link, the one I use for testing, to come up. So, this is an indication that it uses the right Web.Config file.

As for calling the base class implementation, isn't the inherit the line for that? This is pretty much what you had in your example.

The only think I could think of is that is being run locally. So, my URL is something like http://localhost/LevelExtreme20/&.

Another think I could think of is that the main dll to run the Web site is LevelExtreme.dll and Framework.dll is referenced in it.