gridview的删除提示框有关问题

求助gridview的删除提示框问题
错误提示： 未将对象引用设置到对象的实例。 

protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
  {
  if (e.Row.RowType == DataControlRowType.DataRow)
  {
  LinkButton lb = (LinkButton)e.Row.FindControl("lb") as LinkButton;
  lb.Attributes.Add("onclick", "return confirm('确定删除吗？')");
  }
  }

------解决方案--------------------------------------------------------
LinkButton lb = (LinkButton)e.Row.FindControl("lb");
或
 LinkButton lb = e.Row.FindControl("lb") as LinkButton;

------解决方案--------------------------------------------------------
LinkButton lb = e.Row.FindControl("lb") as LinkButton;
if(lb!=null){}

OnClientClick="return confirm('确定删除吗？')"
------解决方案--------------------------------------------------------
一句代码的事情，有必要搞的那么麻烦吗？

C# code

 protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)    {        if (e.Row.RowType.ToString() == "DataRow")        {            ((LinkButton)e.Row.Cells[5].FindControl("LinkButton1")).Attributes.Add("onclick", "return confirm('是否删除')");        }    }
------解决方案--------------------------------------------------------
在页面的控件里加个事件
OnClientClick="return confirm('确定删除吗？')"