Datagrid ItemCommand event not firing

Question

I am still a novice with asp.net, so I'm sure there are better ways to do some of this...

I want to allow a user to enter a date, and then execute an SQL query against a database to return all records matching that date. I want to display those records, and allow the user to select one for additional processing. It seemed like the DataGrid with a column of Pushbuttons was a good choice. In fact, I've done this before, but it those cases there was no user interaction involved. The page just ran a fixed SQL query. With what I'm doing now, the data is displayed as I want, but the Pushbuttons aren't working...the ItemCommand event doesn't fire.

I've read a lot of threads about the ItemCommand event not firing, but I still can't get this to work. My understanding is that I need to bind the DataGrid while not in a Postback, and I think my code does that. When I debug the Page_Load event, I can see that the code inside if (!IsPostBack){} is running, and the session variables have the expected data.

On the page that hosts the DataGrid, I have a 'Find' button that executes a SQL query against a database. The query uses a date entered into the textbox that is on that page. In the 'Find' button click event, I store the results of the query (a DataTable) in a session variable, then do a Redirect to re-load the page.

Once the page reloads, the session variables contain my expected data and the data is displayed in the DataGrid, along with the Pushbuttons. When I click any of the buttons in the DataGrid, the contents of the DataGrid disappear and the ItemCommand event does not fire.

Here's the definition of the DataGrid (updated to include the button):

<asp:Panel runat="server" ID="pnlSelect" HorizontalAlign="Left"  Visible="true" style="margin-top:10px" >
   Please select a participant.
   <asp:DataGrid runat="server" ID="grdItems" AutoGenerateColumns="true" BorderColor="black" BorderWidth="1" CellPadding="3" style="margin-left:2px; margin-top:6px" OnItemCommand="grdSelect_ItemCommand" >
      <Columns>
         <asp:ButtonColumn HeaderStyle-HorizontalAlign="Center" ButtonType="PushButton" Text="Select" HeaderText="Select" CommandName="Select" >
            <ItemStyle Width="60px" HorizontalAlign="Center"/>
         </asp:ButtonColumn>
      </Columns>
   </asp:DataGrid>
</asp:Panel>

Here's the Page Load code (unneeded code-behind stuff is commented out):

protected void Page_Load(object sender, EventArgs e)
{
                if (!IsPostBack)
        {
            if (Session["y"] != null)
            {
                txtFind.Text = Session["x"].ToString();
                DataTable table = Session["y"] as DataTable;
                Session.Remove("x");
                Session.Remove("y");

                if (table != null)
                {
                    /*
                    ButtonColumn buttonColumn = new ButtonColumn
                    {
                        HeaderText = "Select",
                        Text = "Select",
                        CommandName = "Select",
                        ButtonType = ButtonColumnType.PushButton,
                    };

                    grdItems.Columns.Add(buttonColumn);

                    foreach (DataColumn c in table.Columns)
                    {
                        BoundColumn column = new BoundColumn
                        {
                            HeaderText = c.Caption,
                            DataField = c.Caption,
                            ReadOnly = true
                        };

                        grdItems.Columns.Add(column);
                    }
                    */

                    grdItems.DataSource = table;
                    grdItems.DataBind();
                }
            }
        }

}

Here's the relevant 'Find' button event code. I can't post the details of the sql query text, but that part does work and the DataTable does contain the expected data:

DataTable table = DatabaseHelper.FindBySQL(sqlText);

if (table != null && table.Rows.Count > 0)
{
    Session["x"] = searchtext;
    Session["y"] = table;
    Response.Redirect(Request.RawUrl, true);
}

And this the ItemCommand event. I place a breakpoint on the first line, and the debugger never hits it.

protected void grdItems_ItemCommand(object source, DataGridCommandEventArgs e)
{
    string item = "";

    switch (e.CommandName.ToLower())
    {
       case "select":
          item = e.Item.Cells[1].Text.Trim();
          //todo: handle the selected data
          break;
    }
}

Thanks for any thoughts.

Don