Kendo Mvc DropdownList,如何设置初始值

我正在使用带有ajax绑定的Kendo DropdownList.

使用这些代码,我无法设置来自model的初始值.它只是用项目填充列表并选择第一项.

 @(Html.Kendo().DropDownList()
 .Name("NATIONALITY") 
 .DataTextField("DESCRIPTION").HtmlAttributes(new { style = "width:220px" }) 
 .DataValueField("REFERENCEID")
 .Value(Model.NATIONALITY)
         //Placeholder("SELECT")
  .DataSource(source =>
                        {
  source.Read(read =>
             {
        read.Action("GetDefinitionDetails", "Definition", new { definitionCode = "NATIONALITY", addEmptyRow = false });
                            }).ServerFiltering(true);
                            }).ServerFiltering(true);
                        }))

但是当我将Html.Kendo().DropDownList()更改为Html.Kendo().Combobox()时,它还会填充列表并按预期设置初始值(这是模型传递的值).