Data Controls :: Using Calendar Control With GridView

I have a web page with 3 controls:

* Calendar control
* Gridview control for games (uses SqlDataSource1, set to a stored procedure that requires 1 parameter: date)
* Gridview control for videos (uses SqlDataSource2, set to a stored procedure that required 1 parameter: gameID)

This is my intended functionality:

* only control visible at start-up is the calendar control
* user selects a date from the calendar control
* the Game gridview becomes visible, showing games on the date the user selected in the Calendar control
* the user selects a row in the Games gridview
* the Video gridview becomes visible, showing available videos for the game

If I remove the Calendar control, the functionality between the Games gridview and the Videos gridview works as intended:

<asp:GridView ID="GridView1" DataSourceID="SqlDataSource1" DataKeyNames="GameID" AutoGenerateSelectButton="True" runat="server" />
<asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:myConnectionString %>" SelectCommand="usp_SeasonSchedule_GetGamesByDate" SelectCommandType="StoredProcedure">

[Code] ....

However, when I add the Calendar control, and change the datasource of the Games gridview to be dependent on the date selected in the Calendar control, the Video gridview no longer works

<asp:Calendar ID="Calendar1" runat="server"></asp:Calendar>
<asp:GridView ID="GridView1" DataSourceID="SqlDataSource1" DataKeyNames="GameID" AutoGenerateSelectButton="True" runat="server" />
<asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:myConnectionString %>" SelectCommand="usp_SeasonSchedule_GetGamesByDate"

[Code] ....