ASP.Net MVC HTML Helper

<table>        
     <tr>
        <td>
            <span>Account Type Name</span>          
        </td>
        <td>
         @Html.DropDownListFor(model => model.AccountTypeId, new SelectList( ViewBag.AccountTypes, "value", "text"))
         
        </td>
    </tr>
</table>


 public ActionResult AddEditView(string accountSubTypeID)
        {
            AccountSubTypeModel accountSubTypeModel = new AccountSubTypeModel();
            if (!string.IsNullOrEmpty(accountSubTypeID))
            {
                accountSubTypeModel = _subTypeService.SingleOrDefault(new Guid(accountSubTypeID));
            }
           this.LoadDDL(accountSubTypeModel);
            return PartialView(accountSubTypeModel);
        }



private void LoadDDL(AccountSubTypeModel accountSubTypeModel)
        {
            var accountTypes = _typeService.GetDropDownData("Id", "TypeName");
            var selectList = new SelectList(accountTypes, "Value", "Text", accountSubTypeModel.AccountTypeId);
            ViewBag.AccountTypes = selectList;
        }