MVC4 the controller that has not found the path "/" or the controller is not implemented IController

The general MVC project will separate the controller out of the Independent class library, previously used MVC3 always do, test release can run normally, this time with Mvc4, found error: HTTP 404. The resource you are looking for (or one of its dependencies) may have been removed, or its name has changed, or is temporarily unavailable. Please check the following URL and make sure it is spelled correctly. View Exception Log exception: "Path not Found"/"controller or the controller does not implement IController" error. For a day or two, reloading mvc4,. NET Framework, Regiis, swapping servers, the problem still exists. After doing a lot of testing, finally found the problem, the original Controller class library refers to the system MVC4, and the Web layer is a reference to create a project is automatically added to the packages package inside the reference. Delete the Controller class library, re-reference the packages package inside the MVC4, done. The Pit-daddy .......... ......

MVC4 the controller that has not found the path "/" or the controller is not implemented IController