DataGrid嵌套DataGrid,子DataGrid怎么就不执行我添加的事件?

RT下面是部分代码!
private void Page_Load(object sender, System.EventArgs e)
{
// 在此处放置用户代码以初始化页面
if(!this.IsPostBack )
{
dgTitleBind();//绑定父DataGrid
}
this.btnAdds .Attributes .Add ("onclick","return pagecheck()");
}
------------------------------------------------------------------------
private void dgTitle_ItemDataBound(object sender, System.Web.UI.WebControls.DataGridItemEventArgs e)
{
YNJW.CWCN .Business .BLL .testAnswer answer=new YNJW.CWCN.Business.BLL.testAnswer ();
if(e.Item .ItemType ==ListItemType.AlternatingItem ||e.Item .ItemType ==ListItemType.Item )
{
DataGrid dgAnswer=(DataGrid)e.Item .FindControl ("dgAnswer");//找到嵌套在datagrid中的datagrid
dgAnswer.DataSource =answer.GetList ("testId="+dgTitle.DataKeys [e.Item .ItemIndex ].ToString ());//绑定
dgAnswer.DataBind ();
//给子DataGrid添加事件
dgAnswer.CancelCommand += new System.Web.UI.WebControls.DataGridCommandEventHandler(dgAnswer_CancelCommand);
dgAnswer.EditCommand += new System.Web.UI.WebControls.DataGridCommandEventHandler(dgAnswer_EditCommand);
dgAnswer.UpdateCommand += new System.Web.UI.WebControls.DataGridCommandEventHandler(dgAnswer_UpdateCommand);
dgAnswer.DeleteCommand += new System.Web.UI.WebControls.DataGridCommandEventHandler(dgAnswer_DeleteCommand);
}
}
-----------------------------------------------------------------------
//这是子DataGrid控件的编辑事件,但我设过断点,根本就不执行这个事伯嘛.
private void dgAnswer_EditCommand(object source, System.Web.UI.WebControls.DataGridCommandEventArgs e)
{
DataGrid dgAnswer=(DataGrid)e.Item .FindControl ("dgAnswer");
dgAnswer .EditItemIndex =e.Item .ItemIndex ;
dgTitleBind();
}

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为什么我为子控件添加的事件他不执行.是哪做错了嘛!请指点一下.
第一个解决这问题的.给50分!