Http 404 when getting data after ajax post (using web api)

I am getting started with asp.net, ajax / jquery and web api.

I wrote a really basic web application to see what's going on:

Here's the model:

public class Author
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string Surname { get; set; }
}

      

        
        
        
      

    

Here's the controller:

public class AuthorsController : ApiController
{
    List<Author> authors = new List<Author> 
    {
        new Author {Id=1, Name="Alan", Surname="Timo" },
        new Author {Id=2, Name="Jack", Surname="Russel"}
    };


    [HttpGet]
    public IHttpActionResult GetAuthor(int id)
    {
        Author autore = authors.FirstOrDefault(p => p.Id == id);

        if (autore == null)
            return NotFound();
        else
            return Ok(autore);
    }

    [HttpPost]
    public Author PostAutore([FromBody] Author author)
    {          
        authors.Add(author);

        foreach (Author aut in authors)
        {
            Debug.WriteLine(aut.Id + " " + aut.Name + " " + aut.Surname);
        }

        return author;
    }
}

      

        
        
        
      

    

Here's the get and post function in jquery:

function GetAuthorById() {
        var id = $('#authorID').val();
        $.getJSON('api/authors/' + id).done(function (data) {
            alert(data.Name + data.Surname);
        });
    }


    function PostAuthor() {
        var author = {
            Id: $('#newAuthorId').val(),
            Name: $('#newAuthorName').val(),
            Surname: $('#newAuthorSurname').val()
        };

        $.post(
            'api/authors',
            author,
            function (data) {
                alert(data.Name + data.Surname);
            }
        );
    }

      

        
        
        
      

    

My question is about using GET after a successful POST call. Let's say I called the post method, and the controller successfully adds a new Author like {"Id": "3", "Name": "Tom", "Surname": "Cruise"} to the author list (and I'm checking this logging to the console details of each list author in the controller's Mail method). Now if I try a GET like api / authors / 3 I get HTTP 404 and GET with uri 'api / authors / 1' or 'api / authors / 2' gives HTTP 200. Can anyone explain to me why is the server giving me 404 when trying to get data appended with a successful POST?