ASP MVC Html.BeginForm前台传递整个复杂对象至后台问题

Question

我从后台传递了一个强类型Model到前台显示，然后前台建立一个Html.BeginForm表单，并通过object routeValues将整个Model传回后台，但后台接收不到该对象里面的复杂类型数据，具体代码如下：

Model:

    public class FooterViewModel
    {
        public string CompanyName { get; set; }

        public string Year { get; set; }
    }

    public class BaseViewModel
    {
        public string UserName { get; set; }

        public FooterViewModel FooterData { get; set; }
    }

    public class OperateEmployeeViewModel : BaseViewModel
    {
        public int ID { get; set; }
        .......
        .......
     }

View:

@model MVCExample.ViewModels.OperateEmployeeViewModel

@{
    ViewBag.Title = "DeleteEmployee";
}

<h2>Delete Confirmation</h2>

@using (Html.BeginForm("DeleteEmployee", "Employee", Model, FormMethod.Post))
    {
        <table>
            <tr>
                <td>
                    First Name:
                </td>
                <td>
                    @Html.DisplayFor(x => x.FirstName)
                </td>
            </tr>
           ......
    }

Controller:

public ActionResult DeleteEmployee(OperateEmployeeViewModel operateEmployee, string BtnSubmit)
        {
            switch (BtnSubmit)
            {
                case "Delete":
                    Employee e = new Employee();
                    .........
                    .........
                    return RedirectToAction("Index");
                case "Cancel":
                    return RedirectToAction("Index");
            }
            return new EmptyResult();
        }

打了断点，可以看到从后台其他action传递到前台的强类型Model中，FooterData数据不是null的，但从前台beginform传递到后台，action接收到的FooterData却是null，请问这是怎么回事，要怎么解决？