各位大哥大姐 帮忙看看那里有错啊
我怎么一点   ButtonSort_Click     datagrid怎么就不显示拉
我是做一个自动生成datagrid，   ButtonSort_Click从新排序datagrid里的数据

页面代码
<form   id= "Form1 "   method= "post "   runat= "server ">
<asp:button   id= "ButtonCSV "   style= "Z-INDEX:   101;   LEFT:   288px;   POSITION:   absolute;   TOP:   272px "
runat= "server "   Text= "CSV "> </asp:button> <asp:datagrid   id= "DataGrid1 "   style= "Z-INDEX:   105;   LEFT:   184px;   POSITION:   absolute;   TOP:   72px "
runat= "server "   AutoGenerateColumns= "False "   PageSize= "2 ">
<Columns>
<asp:TemplateColumn>
<HeaderTemplate>
<FONT   face= "MS   UI   Gothic "> NO </FONT>
</HeaderTemplate>
<ItemTemplate>
<asp:Button   id= "Button1 "   runat= "server "   Text= " <%#((DataGridItem)Container).ItemIndex+1%> "   CommandName= "Select ">
</asp:Button>
</ItemTemplate>
</asp:TemplateColumn>
</Columns>
</asp:datagrid> <asp:button   id= "ButtonReturn "   style= "Z-INDEX:   102;   LEFT:   352px;   POSITION:   absolute;   TOP:   272px "
runat= "server "   Text= "Return "> </asp:button> <asp:dropdownlist   id= "DropDownList1 "   style= "Z-INDEX:   103;   LEFT:   128px;   POSITION:   absolute;   TOP:   272px "
runat= "server "> </asp:dropdownlist> <asp:button   id= "ButtonSort "   style= "Z-INDEX:   104;   LEFT:   224px;   POSITION:   absolute;   TOP:   272px "
runat= "server "   Text= "Sort "> </asp:button> </form>

页面后台代码

using   System;
using   System.Collections;
using   System.ComponentModel;
using   System.Data;
using   System.Drawing;
using   System.Web;
using   System.Web.SessionState;
using   System.Web.UI;
using   System.Web.UI.WebControls;
using   System.Web.UI.HtmlControls;
using   WebDSP.common;  

namespace   WebDSP
{
///   <summary>
///   Summary   description   for   frmShowTable.
///   </summary>
public   class   frmShowTable   :   System.Web.UI.Page
{
protected   System.Web.UI.WebControls.DropDownList   DropDownList1;
protected   System.Web.UI.WebControls.Button   ButtonCSV;
protected   System.Web.UI.WebControls.Button   ButtonReturn;
protected   System.Web.UI.WebControls.Button   ButtonSort;
protected   String   sql;
protected   System.Web.UI.WebControls.DataGrid   DataGrid1;
protected   DataSet   Dt   =   new   DataSet();

protected   ArrayList   arrayList   =   new   ArrayList();


private   void   Page_Load(object   sender,   System.EventArgs   e)
{
MakeGrid();
if(!Page.IsPostBack)
{
BindGridData();
DropDownListDataBind();
}
}

protected   void   BindGridData()