Dotnet Core Web API Versions

I created my first dotnet web site today and found what I cannot solve. I hope someone can figure out what I am doing wrong.

Here's the code that works as expected.

[Route("api/[controller]")]
public class HelpController : Controller
{
    [HttpGet]
    public string Get()
    {
        return "hello world";
    }
}

      

        
        
        
      

    

However, when I try to apply version control, I get nothing.

[ApiVersion("1.0")]
[Route("api/{version:apiVersion}/[controller]")]
public class HelpController : Controller
{
    [HttpGet]
    public string Get()
    {
        return "hello world";
    }
}

public void ConfigureServices(IServiceCollection services)
{
    // Add framework services.
    services.AddMvc();
    services.AddApiVersioning(option =>
    {
       option.ReportApiVersions = true;
       option.DefaultApiVersion = new ApiVersion(1, 0);
       option.AssumeDefaultVersionWhenUnspecified = true;
    });
}

      

        
        
        
      

    

The code compiles as expected, but I am not getting anything. I think the url should be localhost://.../api/1/help

, but it doesn't work. It sends back 404. I've tried "1", "1.0", "1_0" and "10." Nothing works.

What am I missing?