高手帮忙看一下，GridView控件....我吐得了

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Data.SqlClient;

public partial class GridView2 : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
SetBind();
}
}
private void SetBind()
{
SqlConnection con = new SqlConnection("server=.;database=jinge;uid=sa;pwd=;");
SqlDataAdapter sda = new SqlDataAdapter("select * from News", con);
DataSet ds = new DataSet();
DataTable dt = new DataTable();
sda.Fill(dt);
ds.Tables.Add(dt);
GridView1.DataSource = ds.Tables[0];
GridView1.DataKeyNames = new string[] { "n_id" };
GridView1.DataBind();
}
protected void GridView1_PageIndexChanging(object sender, GridViewPageEventArgs e)
{
GridView1.PageIndex = e.NewPageIndex;
SetBind();
}
protected void GridView1_RowEditing(object sender, GridViewEditEventArgs e)
{
GridView1.EditIndex = e.NewEditIndex;
SetBind();
}

protected void GridView1_RowCancelingEdit(object sender, GridViewCancelEditEventArgs e)
{
GridView1.EditIndex = -1;
SetBind();
}

protected void GridView1_RowUpdating(object sender, GridViewUpdateEventArgs e)
{
string id = GridView1.DataKeys[0].Value.ToString();
[color=#FF0000]string n_id = ((TextBox)GridView1.Rows[e.RowIndex].Cells[1].Controls[0]).Text.ToString().Trim(); //为什么我地方老是报错：指定的参数已超出有效值的范围。参数名: index[/color]
Response.Write(n_id);
}
}