Same as it ever was

So, I've made a bit of progress with my 404 implementation, but I'm encountering a NotImplementedException that I'm not sure how to solve.

I'm trying to implement the solution found here: http://stackoverflow.com/questions/619895/how-can-i-properly-handle-404s-in-asp-net-mvc/2577095#2577095  The difference being, I'm using vanilla Ninject 2.0 as my DI container.

Details of my current problem: http://stackoverflow.com/questions/5808554/asp-net-mvc-2-route-errors-problems-when-using-cottsaks-solution

RequestContext is telling me it needs a string somewhere in its internal dictionary.  I don't see where I'm not supplying it a string.