按钮点击事件未触发并给出错误

我需要有关代码的指导。

 public class FacultyTemplatedynamic:ITemplate
{
    ListItemType ItemType;
    string FieldName;
    string InfoType;
    private bool isEditMode = false;
    protected bool isInEditMode
    {
        get { return this.isEditMode; }
        set { this.isEditMode = value; }
    }
    public FacultyTemplatedynamic(ListItemType itemType, string field_name, string info_type)
    {
        FieldName = field_name;
        ItemType = itemType;
        InfoType = info_type;
    }
    public void InstantiateIn(Control container)
    {
        switch (ItemType)
        {
            case ListItemType.Header:
                Literal header_litrl = new Literal();
                header_litrl.Text = "<b>" + FieldName + "</b>";
                container.Controls.Add(header_litrl);
                break;
            case ListItemType.Item:
                switch (InfoType)
                {
                    case "Command":
                        ImageButton edit_button = new ImageButton();
                        edit_button.ID = "edit_button";
                        edit_button.ImageUrl = "~/Images/edit.gif";
                        edit_button.CommandName = "Edit";
                        edit_button.ToolTip = "Edit";
                        container.Controls.Add(edit_button);
                        break;
                    default:
                        Label field_lbl = new Label();
                        field_lbl.ID = "labelName";
                        //field_lbl.Visible =!(bool) isInEditMode;
                        field_lbl.Text = String.Empty; //we will bind it later through 'OnDataBinding' event
                        field_lbl.DataBinding += new EventHandler(OnDataBinding);
                        container.Controls.Add(field_lbl);
                        break;
                }
                break;
            case ListItemType.EditItem:
                if (InfoType == "Command")
                {
                    ImageButton update_button = new ImageButton();
                    update_button.ID = "update_button";
                    update_button.CommandName = "Update";
                    update_button.ImageUrl = "~/Images/update.gif";
                    update_button.ToolTip = "Update";
                    update_button.OnClientClick = "return confirm('Are you sure to update the record?')";
                    container.Controls.Add(update_button);
                    ImageButton cancel_button = new ImageButton();
                    cancel_button.ImageUrl = "~/Images/cancel.gif";
                    cancel_button.ID = "cancel_button";
                    cancel_button.CommandName = "Cancel";
                    cancel_button.ToolTip = "Cancel";
                    container.Controls.Add(cancel_button);
                }
                else// for other 'non-command' i.e. the key and non key fields, bind textboxes with corresponding field values
                {
                    Label field_lbl1 = new Label();
                    field_lbl1.ID = "LabelEdit";
                    //field_lbl1.Visible = (bool)isInEditMode;
                    field_lbl1.Text = String.Empty; //we will bind it later through 'OnDataBinding' event
                    field_lbl1.DataBinding += new EventHandler(OnDataBinding);
                    container.Controls.Add(field_lbl1);
                }
                break;
        }
    }
    private void OnDataBinding(object sender, EventArgs e)
    {
        object bound_value_obj = null;
        Control ctrl = (Control)sender;
        IDataItemContainer data_item_container = (IDataItemContainer)ctrl.NamingContainer;
        bound_value_obj = DataBinder.Eval(data_item_container.DataItem, FieldName);
        switch (ItemType)
        {
            case ListItemType.Item:
                Label field_ltrl = (Label)sender;
                field_ltrl.Text = bound_value_obj.ToString();
                break;
            case ListItemType.EditItem:
                TextBox field_txtbox = (TextBox)sender;
                field_txtbox.Text = bound_value_obj.ToString();
                break;
        }
    }
}


 private void CreateTemplatedGridView()
        {
            PopulateTable();
            for (int i = 0; i < dt.Columns.Count; i++)
            {
                TemplateField tf = new TemplateField();
                tf.HeaderTemplate = new FacultyTemplatedynamic(ListItemType.Header, dt.Columns[i].ColumnName, dt.Columns[i].DataType.Name);
                tf.ItemTemplate = new FacultyTemplatedynamic(ListItemType.Item, dt.Columns[i].ColumnName, dt.Columns[i].DataType.Name);
                tf.EditItemTemplate = new FacultyTemplatedynamic(ListItemType.EditItem, dt.Columns[i].ColumnName, dt.Columns[i].DataType.Name);
                GrdMarkAttendance.Columns.Add(tf);
            }
            TemplateField tf1 = new TemplateField();
            GrdMarkAttendance.Columns.Add(tf1);
            GrdMarkAttendance.DataSource = dt;
            GrdMarkAttendance.DataBind();
        }
     private void PopulateTable()
        {
            dt = new DataTable();
            dt = obj.GetRegister();
        }    
     protected void GrdMarkAttendance_RowDataBound(object sender, GridViewRowEventArgs e)
        {
            PopulateTable();
            int i = dt.Columns.Count;          
            if (e.Row.RowType == DataControlRowType.DataRow)
            {
                DropDownList ddl = new DropDownList();
                ddl.ID = "ddl";
                ddl.Items.Insert(0, "Present");
                ddl.Items.Insert(1, "Absent");
                ddl.Items.Insert(2, "Leave");              
                e.Row.Cells[i].Controls.Add(ddl);
            }
        }    
    protected void Button1_Click(object sender, EventArgs e)
        {
        }  

当我运行此页面并单击按钮时，我得到以下错误：

"/"应用程序中的服务器错误

找到多个ID为"labelName"的控件。FindControl要求控件具有唯一的ID

描述：在执行当前web*请求期间发生未处理的异常。请查看堆栈跟踪以了解有关错误以及错误**在代码中的来源的更多信息。*

异常详细信息：System.Web.HttpException：找到多个具有相同ID'labelName'的控件**FindControl**要求控件具有唯一的ID

*源错误：*

在执行当前web请求期间生成了一个未处理的异常*有关异常起源和位置的信息可以使用*下面的异常堆栈跟踪

*堆栈跟踪：*

*[HttpException (0x80004005): Multiple controls with the same ID 'labelName' were found.* *FindControl requires that controls have unique IDs.]*
  *System.Web.UI.Control.FillNamedControlsTable(Control namingContainer, ControlCollection* *controls) +265*
  *System.Web.UI.Control.FillNamedControlsTable(Control namingContainer, ControlCollection*    * controls)* +311
   *System.Web.UI.Control.FindControl(String id, Int32 pathOffset) +145*
   *System.Web.UI.Control.FindControl(String id, Int32 pathOffset) +365*
   *System.Web.UI.Control.FindControl(String id, Int32 pathOffset) +365*
   *System.Web.UI.Control.FindControl(String id, Int32 pathOffset) +365*
   *System.Web.UI.Control.FindControl(String id, Int32 pathOffset) +365*
   *System.Web.UI.Page.FindControl(String id) +38*
   *System.Web.UI.Page.ProcessPostData(NameValueCollection postData, Boolean fBeforeLoad)*  +287 
   *System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean*  *includeStagesAfterAsyncPoint) +4911*  

• 我不知道为什么昨天会出现这个错误，它写得很好，但当我使用*时FindControl在行的特定单元格中它开始给我错误，但现在我删除了*该代码，单击按钮后它显示错误。*请给出您的***建议，以便我可以进一步移动

如果我以错误的格式发布问题或提供的数据不足，很抱歉