I'm having trouble using SimpleInjector with MVC4/Web API, I've installed it as per the MVC3 way and in SimpleInjectorInitializer::InitializeContainer() I register my repository, however when I execute a controller that uses this repository I get:

Type 'Core.Controllers.CountryController' does not have a default constructor

It seems that the problem may be down to the controller type, Controller normally implements IController etc, however under the new Web API the ApiController class is defined as:

public abstract class ApiController : IHttpController, IDisposable

Whilst in your code you explicitly check for IController compatibility so the controller is never found :/

Take a look at this stackoverflow answer. It will answer your question.