GridView / model绑定UpdateMethod未被调用

我有一个基本的Web表单项目使用实体框架&SQL Server用于数据。我试图将GridView连接到一个表，由于某种原因，UpdateMethod没有被调用。当点击"更新"链接时，它会回发，但它永远不会到达gvNames_UpdateItem。如有任何帮助，我将不胜感激。

<asp:GridView ID="gvNames" runat="server" SelectMethod="gvNames_GetData" UpdateMethod="gvNames_UpdateItem"
    DeleteMethod="gvNames_DeleteItem" CssClass="table table-hover table-striped"
    UseAccessibleHeader="true" ItemType="CountyPMFraudData.NotifyName" AutoGenerateColumns="false" DataKeyNames="NotifyNamesID" 
    ShowHeaderWhenEmpty="true" OnPreRender="gvNames_PreRender" >
    <Columns>
        <asp:DynamicField DataField="NotifyNamesID" Visible="false" />
        <asp:DynamicField DataField="UserID" Visible="false" />
        <asp:DynamicField DataField="CorpFlag" HeaderText="Business" />
        <asp:DynamicField DataField="FirstName" />
        <asp:DynamicField DataField="LastName" HeaderText="Last Name/Business Name" />
        <asp:DynamicField DataField="Active" HeaderText="Active" />
        <asp:CommandField ShowEditButton="true" ShowCancelButton="true" ShowDeleteButton="true"/>
    </Columns>
</asp:GridView>

后面的代码是:

public void gvNames_DeleteItem(int notifyNamesID)
{
    using (var dbContext = new CountyPMFraudEntities())
    {
        var item = new NotifyName { NotifyNamesID = notifyNamesID };
        dbContext.Entry(item).State = EntityState.Deleted;
        try
        {
            dbContext.SaveChanges();
        }
        catch (DbUpdateConcurrencyException)
        {
            ValidationError.Display(String.Format("Item with id {0} no longer exists in the database.", notifyNamesID));
        }
    }
}
public IEnumerable gvNames_GetData()
{
    List<NotifyName> names = null;
    if (HttpContext.Current.User.Identity.IsAuthenticated)
    {                
        using (var dbContext = new CountyPMFraudEntities())
        {
            names = dbContext.NotifyNames.Where(NotifyName => NotifyName.UserID == _userID).ToList();
        }
    }
    return names;
}
public void gvNames_UpdateItem(int notifyNamesID)
{
    using (var dbContext = new CountyPMFraudEntities())
    {
        var name = dbContext.NotifyNames.Find(notifyNamesID);
        if (name == null)
        {                    
            ValidationError.Display(String.Format("Item with id {0} was not found", notifyNamesID));
            return;
        }
        TryUpdateModel(name);
        if (ModelState.IsValid)
        {
            dbContext.SaveChanges();
        }
    }
}
protected void gvNames_PreRender(object sender, EventArgs e)
{
    try
    {
        gvNames.HeaderRow.TableSection = TableRowSection.TableHeader;
    }
    catch (Exception)
    {
        //Just ignore becuase there is no data.
    }
}