DetailsView not working with selectable GridView
<p>My DetailsView is always blank.  I've tested both Data Sources in QueryBuilder and they return values.  I suspect something is wrong with the parameter value assignments in PoweredEquipDetails where they are set to the SelectedValue in GridView1, but I don't know why it wouldn't work.</p>

<pre><code>&lt;body&gt;
 &lt;form id="form1" runat="server"&gt;
  &lt;asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" 
    DataSourceID="PoweredEquipHeader" DataKeyNames="Model,Serial"&gt;
    &lt;Columns&gt;
        &lt;asp:CommandField ShowSelectButton="True" /&gt;
        &lt;asp:BoundField DataField="Model" HeaderText="Model" ReadOnly="True" 
            SortExpression="Model" /&gt;
        &lt;asp:BoundField DataField="Serial" HeaderText="Serial" ReadOnly="True" 
            SortExpression="Serial" /&gt;
    &lt;/Columns&gt;
    &lt;SelectedRowStyle BackColor="#FF6600" /&gt;
  &lt;/asp:GridView&gt;
  &lt;asp:SqlDataSource ID="PoweredEquipHeader" runat="server" 
    ConnectionString="&lt;%$ ConnectionStrings:CPECConnectionString %&gt;" 
    SelectCommand="Select t1.Model, t1.Serial From Powered_Equip t1 Where TechID = @TechID And Store = @Store"&gt;
    &lt;SelectParameters&gt;
        &lt;asp:QueryStringParameter DefaultValue="TECH01" Name="TechID" 
            QueryStringField="Tech" /&gt;
            &lt;asp:QueryStringParameter DefaultValue="0000" Name="Store" 
            QueryStringField="Store" /&gt;
    &lt;/SelectParameters&gt;
  &lt;/asp:SqlDataSource&gt;
  &lt;asp:SqlDataSource ID="PoweredEquipDetail" runat="server" 
    ConnectionString="&lt;%$ ConnectionStrings:CPECConnectionString %&gt;" 
    SelectCommand="SELECT t1.Serial, t1.Model, t1.Status, t1.[Trailer VIN], t2.Tag, t2.State, t2.ExpMonth, t2.ExpYear FROM Powered_Equip AS t1 INNER JOIN Trailers AS t2 ON t1.[Trailer VIN] = t2.VIN WHERE (t1.Serial = @Serial) AND (t1.Model = @Model)"&gt;
    &lt;SelectParameters&gt;
        &lt;asp:ControlParameter ControlID="GridView1" Name="Serial" 
            PropertyName="SelectedValue" /&gt;
        &lt;asp:ControlParameter ControlID="GridView1" Name="Model" 
            PropertyName="SelectedValue" /&gt;
    &lt;/SelectParameters&gt;
&lt;/asp:SqlDataSource&gt;
&lt;asp:DetailsView ID="DetailsView1" runat="server"
    DataSourceID="PoweredEquipDetail" DataKeyNames="Serial,Model"&gt;
    &lt;Fields&gt;
        &lt;asp:BoundField DataField="Serial" HeaderText="Serial" ReadOnly="True" 
            SortExpression="Serial" /&gt;
        &lt;asp:BoundField DataField="Model" HeaderText="Model" 
            ReadOnly="True" SortExpression="Model" /&gt;
        &lt;asp:BoundField DataField="Status" HeaderText="Status" ReadOnly="True" 
            SortExpression="Status" /&gt;
        &lt;asp:BoundField DataField="Trailer VIN" HeaderText="Trailer VIN" ReadOnly="True" 
            SortExpression="Trailer VIN" /&gt;
        &lt;asp:BoundField DataField="Tag" HeaderText="Tag" ReadOnly="True" 
            SortExpression="Tag" /&gt;
        &lt;asp:BoundField DataField="State" HeaderText="State" ReadOnly="True" 
            SortExpression="State" /&gt;
        &lt;asp:BoundField DataField="ExpMonth" HeaderText="ExpMonth" ReadOnly="True" 
            SortExpression="ExpMonth" /&gt;
        &lt;asp:BoundField DataField="ExpYear" HeaderText="ExpYear" ReadOnly="True" 
            SortExpression="ExpYear" /&gt;
    &lt;/Fields&gt;
&lt;/asp:DetailsView&gt;
&lt;/form&gt;
</code></pre>

<p></p>

<p>EDIT:  So I believe what is happening is the GridView's SelectedValue in the DetailsView parameter assignments is always Model, instead of both Model and Serial as specified in my DataValueKeys.  In the event that an equipment item has a model and serial that are the same value (i.e. Model 118 Serial 118), the DetailsView populates.  But in any case where the Model and Serial are different (which will be almost every other case), the DetailsView is blank.  So how do I get two different SelectedValues to assign value to two different ControlParameters?</p>
