How To Send Parameters From SqlDataSource?

I'm try to use a SqlDataSource control for binding data (stored procedure) to a GridView control. But I only get the error message below. What am I doing wrong?

 
 ----------- Error message ----------------------
Procedure or function 'StatisticCustomers' expects parameter '@From', which
was not supplied.

 
------------- Customer.aspx -------------------- 
            From <asp:TextBox id="txtDateFrom" CssClass="datebox" runat="server"></asp:TextBox>
            To <asp:TextBox id="txtDateTo" CssClass="datebox" runat="server"></asp:TextBox>
            Min: <asp:TextBox id="txtMinimumOrders" CssClass="" runat="server"></asp:TextBox>
 
     <asp:GridView ID="grdvwCustomers" AllowPaging="True" AllowSorting="True" DataSourceID="SqlDataSource1" runat="server" AutoGenerateColumns="False">
        <Columns>
            <asp:BoundField DataField="UserId" HeaderText="UserId" SortExpression="UserId" />
            <asp:BoundField DataField="Column1" HeaderText="Column1" ReadOnly="True" SortExpression="Column1" />
            <asp:BoundField DataField="Items" HeaderText="Items" ReadOnly="True" SortExpression="Items" />
            <asp:BoundField DataField="Column2" HeaderText="Column2" ReadOnly="True" SortExpression="Column2" />
        </Columns>
    </asp:GridView>
    
  
    <asp:SqlDataSource ID="SqlDataSource1" ConnectionString="<%$ ConnectionStrings:LocalSqlServer %>" SelectCommand="StatisticCustomers" SelectCommandType="StoredProcedure" runat="server">
        <SelectParameters>
            <asp:ControlParameter ControlID="txtDateFrom" Name="dtFrom" PropertyName="Text" Type="DateTime" />
            <asp:ControlParameter ControlID="txtDateTo" Name="dtTo" PropertyName="Text" Type="DateTime" />
            <asp:ControlParameter ControlID="txtMinimumOrders" Name="iMinimumOrders" PropertyName="Text" Type="Int32" />
        </SelectParameters>
    </asp:SqlDataSource>

 
 
ALTER PROCEDURE [dbo].[StatisticCustomers]
    (@From datetime,
    @To datetime,
    @MinimumOrders int )
AS
    SELECT
        Orders.UserId, 'name', COUNT(*) AS Items, SUM(OrderDetail.Subtotal)
    FROM
        Orders INNER JOIN OrderDetail ON Orders.OrderId = OrderDetail.OrderId
    WHERE
        DateCreated > @From AND DateCreated < @To
    GROUP BY
        Orders.UserId
    ORDER BY
        Items DESC
 
Regards, Sigurd