I might be remembering this completely wrong, but I thought the "input" attribute had to be an action, JSP, tile, etc. rather than a forward--there was a way to configure this via the controller's "inputForward" attribute (see here).
I'm not too sure about this though. A quick way to sanity-check this would be to try using the JSP name directly. If it works, I might actually be right. If it's still broken, then it's something else still.