MVC does not compile views into DLL's, but instead references them as files from the root of your site directory. The location, by convention is ~/Views and a search path is followed. This is more or less hard coded into the default view engines.
Because Views are files, when you break them into a separate project, they won't exist in your primary web application project. Thus, the view engine can't find them. When you compile the app, any projects referenced will only copy the DLL's (and potentially a few other things, like pdb's, etc.)
Now, there are ways to work around this, but to be honest, they're usually more trouble than they're worth. You can look into "Portable Areas" in the mvc contrib project, but these are not well supported and there's been talk of replacing them with NuGet packaging.
You can also follow @mo.esmp's advice, and create a custom view engine, but you'll still need to figure out ways to copy the Views somewhere the site can access them upon build and/or deploy.
My suggestion would be to NOT break out projects in the manner you describe. I don't see any value in it. If your project becomes so large, I would instead separate your code into areas, and keep all your area code and data together.
What value is there in separating items that are clearly dependent upon each other into separate assemblies who's only purpose is to collect things based on their purpose? I see some value in separating models into their own project, since models can be used by more than one assembly. Controllers and views, however, are only ever used by the MVC primary site.
ehsan
that is also possible . But making things complex right – Knobby