checkboxes matrix with MVC4

I need to disply a matrix of checkboxes like the one in here asp.net mvc checkbox/radiobutton matrix model-binding

well, instead of subquestions I haves roles and types, so here is my code:

my models:

public class role
{
    public role()
    {
        types = new List<role_type>();
    }

    [Key]
    public int role_id { get; set; }
    public string role_name { get; set; }
    public int role_value { get; set; }
    public Boolean IsSelected { get; set; }

    public IList<role_type> types { get; set; }
}

public class role_type
{
    public int Id { get; set; }
    public Boolean IsSelected { get; set; }
    public string type { get; set; }
}

My view Model:

public class roleViewModel
{
    public roleViewModel()
    {
        Roles = new List<role>();
    }
    public int ID { get; set; }

    public IList<role> Roles { get; set; }
}

My controller:

public class roleviewmodelController : Controller
{
    private Context db = new Context();

    [HttpGet]
    public ActionResult Index(roleViewModel rvm)
    {
        return View(rvm);
    }
}

and my view

@model UsersManagement.Models.roleViewModel
@{
    ViewBag.Title = "Index";
}


@for (var i = 0; i < Model.Roles.Count(); i++)
{
  <div id="roles">            
    <ul>
      @for (var j = 0; j <4; j++)
      {
        <li>@Html.CheckBoxFor(m=>Model.Roles[i].types[j].IsSelected)</li>
      }
    </ul>  
  </div>
 }

this doesn't display anything, what am i missing?

the types should be like (Edit, Delete, Read, Create) and the roles like: manage companies, manage invoices, etc...

PS: My final goal is to customise the authorization system but this is another issue.