You probably need to install ASP.Net Webpages. You can get it along with MVC4 using the standalone installer here: http://www.asp.net/mvc/mvc4
Also, did you enable ASP.Net webpages in web.config?
<add key="webpages:Enabled" value="true" />
webPages:enabled with value false prevents .cshtml or .vbhtml files in the Views folder from being directly accessible from a web browser.