带有子控件的asp.net Web服务器控件,事件未触发

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>

protected void Page_Load(object sender, EventArgs e)
{
    ChildControl.EventName += new EventHandler(ChildControl_EventName);
}

void ChildControl_EventName(object sender, EventArgs e)
{
    // 处理事件
}

protected void Button_Click(object sender, EventArgs e)
{
    RaiseEvent(new EventArgs());
}

protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        CreateChildControl();
    }
}

private void CreateChildControl()
{
    ChildControl childControl = new ChildControl();
    childControl.EventName += new EventHandler(ChildControl_EventName);
    PlaceHolder.Controls.Add(childControl);
}

void ChildControl_EventName(object sender, EventArgs e)
{
    // 处理事件
}