HttpHandler IIS Config Problem

Delvign into the world of httpHandlers, and it looks like pretty much EVERYONE has written a tutorial on how to get them going - but there's not much info on keeping them going. My problem was that IIS was refusing to pass the request to the HttpHandler, and kept spitting out a 404 instead (I'm testing with paths to files that do not exist, planning to map them dynamically (and yes I know there are a number of ways to do this)).

Anyhow - spent the morning trying to figure out what I forgot to do: Checked the config file, made sure the assembly was there (expieremented with adding X's to the config settings, and renaming the assembly to verify that linkage was perforing) The stub protodevelopment site is working on one machine, but not on a staging server I need to test it on.

Eventually I decided to just start over and create a new Virtual Directory - and it just started working. Doing nothing different - it just working. I suspect it is an IIS metabase problem.