Can't Get Sqldatasource To Return Results From A Stored Procedure

I thought I would impliment a new feature of my web page using stored procedures and the SqlDataSource object, for practice or whatever, since I don't normally use that stuff.

This is the stored procedure:set ANSI_NULLS ON
set QUOTED_IDENTIFIER ON
go

-- =============================================
-- Author:Lance Colton
-- Create date: 7/31/06
-- Description:Find the contest winner
-- =============================================

ALTER PROCEDURE [dbo].[AppcheckContest]
-- Add the parameters for the stored procedure here

@BeginDate datetime = '1/1/2006',
@EndDate datetime = '12/31/2006',
@SectionID int = 10,
@WinnerID int = 0 OUTPUT
AS
BEGIN
-- SET NOCOUNT ON added to prevent extra result sets from
-- interfering with SELECT statements.

SET NOCOUNT ON;

-- Insert statements for procedure here

SELECT top 1 @WinnerID = P.UserID
FROM cs_Posts P
WHERE P.PostDate BETWEEN @BeginDate AND @EndDate
AND P.SectionID = @SectionID
AND P.UserID <> 2100 -- I don't want to win my own contest...

AND SettingsID = 1000 -- This number could be different if i had more than one CS installed?

AND IsApproved = 1
ORDER BY NEWID() -- yes this is slow, but it works...

RETURN @WinnerID
END

 It's really simple - just needs to return the one randomly chosen integer userID. I've tested it in query designer or whatever it's called in Management Studio and it works fine there at least.

Thinking I was done the hard part, I created a new web form in visual studio, dropped a SqlDataSource on it, and used the 'configure data source' wizard from the smart tag to do all the work for me. I didn't have any trouble using the wizard to select my stored procedure, and i'm using the sa connection string to simplify my debugging. I tried using the FormParameter / FormField way of getting the output and setting the input parameters. I can't seem to get it working though. There's no errors or anything, just the output isn't coming through.

Here's the code from the aspx codebehind file:Partial Class Contest
Inherits System.Web.UI.Page

Protected Sub btnSelectWinner_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnSelectWinner.Click
Dim stuff As New System.Web.UI.DataSourceSelectArguments
SqlDataSource1.Select(stuff)
SqlDataSource1.DataBind()
lblWinnerID.Text = SqlDataSource1.SelectParameters("WinnerID").ToString
End Sub
End Class

 As you can see, I wasn't sure if you're supposed to call databind() or select() to actually get the stored procedure to execute, so I tried both. I was hoping the last line of code there would set the label to the value contained in the @WinnerID parameter, but instead it sets it to "WinnerID".

Here's the code from the .aspx file. Most of this was generated by the Wizard, but I messed around with it a bit. <%@ Page Language="VB" MasterPageFile="~/MasterPage.master" AutoEventWireup="false" CodeFile="Contest.aspx.vb" Inherits="Contest" title="Untitled Page" %>
<asp:Content ID="Content1" ContentPlaceHolderID="CPHMain" Runat="Server">
<asp:Button ID="btnSelectWinner" runat="server" Text="Find Winner" />
<asp:Calendar ID="Calendar_From" runat="server"></asp:Calendar>
<asp:Calendar ID="Calendar_To" runat="server"></asp:Calendar>
<asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:appcheck-csConnectionString-sa %>"
SelectCommand="AppcheckContest" SelectCommandType="StoredProcedure" CancelSelectOnNullParameter="False">
<SelectParameters>
<asp:FormParameter FormField="Calendar_From" Name="BeginDate" Type="DateTime" />
<asp:FormParameter FormField="Calendar_To" Name="EndDate" Type="DateTime" />
<asp:Parameter DefaultValue="10" Name="SectionID" Type="Int32" />
<asp:formParameter FormField="lblWinnerID" defaultvalue="666" Direction="InputOutput" Name="WinnerID" Type="Int32" />
</SelectParameters>
</asp:SqlDataSource>
 
<asp:Label ID="lblWinnerID" runat="server" Text="???"></asp:Label>
</asp:Content>