grid-источник данных хранимой процедуры

Question

у меня есть сетка

  <asp:GridView ID="grid1" runat="server" DataSourceID="titleDataSource" 
    AutoGenerateColumns="False" DataKeyNames="ClassID" >
  <Columns>
      <asp:BoundField DataField="ID" HeaderText="ID" InsertVisible="False" 
          ReadOnly="True" SortExpression="ID" />
      <asp:BoundField DataField="ClassID" HeaderText="ClassID" ReadOnly="True" 
          SortExpression="ClassID" />
      <asp:BoundField DataField="ClassName" HeaderText="ClassName" 
          SortExpression="ClassName" />
      <asp:BoundField DataField="ClassTime" HeaderText="ClassTime" 
          SortExpression="ClassTime" />
      <asp:BoundField DataField="ClassDate" HeaderText="ClassDate" 
          SortExpression="ClassDate" />
      <asp:BoundField DataField="ClassDay" HeaderText="ClassDay" 
          SortExpression="ClassDay" />
      <asp:BoundField DataField="ClassMonth" HeaderText="ClassMonth" 
          SortExpression="ClassMonth" />
      <asp:BoundField DataField="ClassLocation" HeaderText="ClassLocation" 
          SortExpression="ClassLocation" />
      <asp:BoundField DataField="ClassNotes" HeaderText="ClassNotes" 
          SortExpression="ClassNotes" />
      <asp:CheckBoxField DataField="show" HeaderText="show" SortExpression="show" />
      <asp:CheckBoxField DataField="isOnline" HeaderText="isOnline" 
          SortExpression="isOnline" />
      <asp:BoundField DataField="fromTime" HeaderText="fromTime" 
          SortExpression="fromTime" />
      <asp:BoundField DataField="ToTime" HeaderText="ToTime" 
          SortExpression="ToTime" />
      <asp:BoundField DataField="Type" HeaderText="Type" SortExpression="Type" />
      <asp:BoundField DataField="LocationID" HeaderText="LocationID" 
          SortExpression="LocationID" />
      <asp:BoundField DataField="ProviderID" HeaderText="ProviderID" 
          SortExpression="ProviderID" />
      <asp:BoundField DataField="ClassCID" HeaderText="ClassCID" 
          SortExpression="ClassCID" />
  </Columns>
</asp:GridView>
 <asp:SqlDataSource ID="titleDataSource" runat="server" 
    ConnectionString="<%$ ConnectionStrings:nvpt4 %>" 
    SelectCommand="getClassesByCandP" SelectCommandType="StoredProcedure">
    <SelectParameters>
        <asp:ControlParameter ControlID="classList" DefaultValue="" Name="ClassCID" 
            PropertyName="SelectedValue" Type="Int32" />
        <asp:ControlParameter ControlID="providerslist" DefaultValue="" 
            Name="ProviderID" PropertyName="SelectedValue" Type="Int32" />
    </SelectParameters>
</asp:SqlDataSource>

ТАК, 2 элемента управления в sqldatasource - не что иное, как выпадающие списки, которые я отправляю хранимой процедуре в качестве ввода

 <asp:DropDownList  ID="classList" runat="server" AutoPostBack="true"  ></asp:DropDownList>
<asp:DropDownList ID="providerslist" runat="server" AutoPostBack="true"  >
</asp:DropDownList>

Это моя хранимая процедура

 ALTER PROCEDURE [dbo].[getClassesByCandP] 
(@ClassCID int= NULL,
  @ProviderID int= NULL)  
 AS 
BEGIN  

SELECT CI.[ID]  
  ,[ClassID]
  ,[ClassName]
  ,[ClassTime]
  ,[ClassDate]
  ,[ClassDay]
  ,[ClassMonth]
  ,[ClassLocation]
  ,[ClassNotes]
  ,[show]
  ,[isOnline]
  ,[fromTime]
  ,[ToTime]
  ,[Type]
  ,[LocationID]
  ,[ProviderID]
  ,[ClassCID]
 FROM [nvpt4].[dbo].[ClassInfo] CI

 WHERE ((CI.ClassCID = @ClassCID) OR (@ClassCID IS NULL)) 
 AND ((CI.ProviderID = @ProviderID) OR(@ProviderID IS NULL)) 
 OPTION(RECOMPILE)
 END

Итак, когда я бегу, я не получаю сетку на экране. Можете ли вы сообщить мне ошибку, которую я делал?