I had some trouble today figuring out why sorting a dataset wasn't working.  Basically my SQL statement put an ORDER BY 'column' DESC but when I dumped it into a dataset, for some reason the order disappeared.  I figured out that in order to sort a DataSet, you actually have to put the data inside that DataSet into something like a DataView.  Then, you sort the DataView with myView.Sort. Here's my sample, working code.

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;
using System.Data.Sql;
using System.Collections.Generic;
using Microsoft.ApplicationBlocks.Data;

 public void GetItemNumber()
        {
                string sConnectionString = "Data Source=sqlserver;Database=MY-DATABASE-NAME;uid=userid;pwd=password";
                SqlConnection objConn = new SqlConnection(sConnectionString);
                objConn = new SqlConnection(sConnectionString);
                objConn.Open();
                try
                {
                    string MySQLStatement =
                        "SELECT ItemNumber FROM ItemTable where ItemNumber " +
                        "LIKE '%" + this.txtItemumber.Text + "%' ORDER BY ItemNumber DESC";  //this DESC doesn't seem to do anything.

                   using (SqlDataAdapter da = new SqlDataAdapter(MySQLStatement, objConn))
                    {

                       //fill the DataSet

                        DataSet ds = new DataSet();
                        da.Fill(ds);
                      //Create DataView using the data in my DataSet.
                        DataView myView = new DataView();
                        myView = ds.Tables[0].DefaultView;

                     //sort in DESC order with ColumnName

                       myView.Sort = "ItemNumber DESC";

                        foreach (DataRow dr in ds.Tables[0].Rows)
                       {
                           this.txtOutputItemNumber.Text = myView[0].Row[0].ToString();
                        }
                    }
                }
                catch (System.Exception e)
                {
                    this.lblErrors.Text = e.Message.ToString();
                }
                finally
                {
                 objConn.Close();
                }
        }

That should save somebody some time some day.  If this helps you and you use it, please post a comment or link to this post.  Thanks!