asp.net-mvc - Custom EditorFor and ICollection issue

Question

I'm doing this

using (var db = new MyContext())
{
    var g = new MyGroup
    {
        Caracteristicas = db.Caracteristicas.ToList()
    };
    return View(g);
}

and getting this exception when trying to display that data:

The ObjectContext instance has been disposed and can no longer be used for operations that require a connection.

View:

@Html.EditorFor(m => m.Caracteristicas)

Custom editor:

@model Exemplo.Models.Caracteristica
<label class="checkbox">@Html.CheckBoxFor(m => m.Valor) @Model.Nome</label> 

SOLVED (in part)

The problem was that I mismatched the name of the custom editor file.

But now that this little mistake is fixed, however, all Ids (in bind) are zero... how to solve that? :(

This is the output:

<label class="checkbox">
  <input data-val="true" data-val-required="The Valor field is required." id="Caracteristicas_0__Valor" name="Caracteristicas[0].Valor" type="checkbox" value="true" />
  <input name="Caracteristicas[0].Valor" type="hidden" value="false" />
  OldItem</label>

"value" shouldn't be the Id? :(