I don't think the problem is with your routes, I believe it is caused by moving your View and Controller folders to the App folder.
MVC use "convention over configuration" for stuff like where the folders are located, I'm guessing it can't find the Views/Controllers in the new folders?
From here:
These folders are included even in an
Empty ASP.NET MVC application because
the ASP.NET MVC framework by default
uses a “convention over configuration”
approach and makes some default
assumptions based on folder naming
conventions. For instance, controllers
look for views in the Views folder by
default without you having to
explicitly specify this in your code.
Sticking with the default conventions
reduces the amount of code you need to
write, and can also make it easier for
other developers to understand your
project.
I'm not saying that it's not possible to have a folder structure like you have, I just dont believe its supported out of the box.
Personally I'd recommend moving back to the default, if you need to keep this structure then I think you may need to implement your own ControllerFactory and ViewEngine (I'm not sure if these are the correct hooks that you would need to change).
Edit:
Are you trying to implement App as an Area?
Edit2:
If you are trying to add App as an area there are some steps you will need to follow, The reason I wasn't sure if this was what you were trying to do is because I thought areas had to exist within an Areas folder.
There are some steps outlines here Including how to register your area if that is what you are trying to do.