How to show a list of checkbox according to a Drop

I am developing an ASP .Net MVC 3 application using C# and SQL Server 2005.

I am using also Entity Framework and Code First Method.

I have a view 'Application' which contain a DropDownList and a Table.

The items of DropDownList are being loaded from the base (Table=Genre) in form of a list.

According to the selected item in the DropDownList, I want didplay some values (list) in the base in form of CheckBox in the table.

I tried CheckBoxFor but it's not working.

This is the View :

 <div>         
         <%:Html.Label("Type :")%><%: Html.DropDownListFor(model => model.SelectedGenre, Model.GenreItems)%>

   </div>

   <table border = "transparent">
    <tr>
        <th>

        </th>

        </tr>

        <% foreach (var item in Model.FaItems) { %>
    <tr>
         <td>

            <%: Html:CheckBoxFor (modelItem => item.Nom_Famille) %>
        </td>


    </tr>
     <% } %>

    </table>

and this is the Controller :

[HttpGet]
        public ActionResult Application(Genre genre)
        {
            var vv = new FlowViewModel();

            vv.GenreItems = new SelectList(db.Genres.ToList(), "ID_G", "ID_G");


            if (vv.SelectedGenre == "Famille")
            {

                vv.FaItems = db.Familles.ToList();


            }
            else if (vv.SelectedGenre == "Sous Famille")
            {
                vv.SFItems = db.Sous_Familles.ToList();

            }
            return View(vv);

        }

and this is the model :

public class FlowViewModel
{

    [Key]
    public string IDv { get; set; }

    public List<Famille> FaItems { get; set; }
    public List<Sous_Famille> SFItems { get; set; }
    [NotMapped]
    public SelectList GenreItems { get; set; }
    public string SelectedGenre { get; set; } 

    public FlowViewModel()
    {
        FaItems = new List<Famille>();
        SFItems = new List<Sous_Famille>();
    }
}

NOTE :

I want choose some values of the list (check them) and record that in the base, if you have any another suggestion except checkbox, that's will be very useful. Thanks.

For Showing User Roles in checkboxes I did the FOllowing, you can find your way. the difference is that, I did in Razor

             @{
                var roles = (SimpleRoleProvider)Roles.Provider;
                string[] strroles = roles.GetAllRoles();
                string[] userorles = roles.GetRolesForUser(Model.UserName);
                foreach (string strrole in strroles)
                {
                    bool isinrol = false;
                    foreach (string struserroles in userorles)
                    {
                        if (strrole == struserroles)
                        {
                            isinrol = true;
                        }
                    }
                    if(isinrol)
                    {
                        <input type="checkbox" id="roles[]"  name="roles" value="@strrole" checked="checked" /> @strrole <br />
                    }
                    else
                    {
                        <input type="checkbox" id="roles[]" name="roles"  value="@strrole"/> @strrole <br />
                    }
                }
              }