Update error in GridView

[RobertTheProgrammer]

Hi,

This should be ridiculously simple, but I just can't get the update to work in GridView for ASP.NET. Here's the very simplified code:

            <asp:SqlDataSource id="ProductsSource" Runat="Server"
                ConnectionString="<%$ ConnectionStrings:ConnectionStringTraining %>"
                ProviderName="<%$ ConnectionStrings:ConnectionStringTraining.ProviderName %>"
                SelectCommand="SELECT training_unit_id, training_unit_name FROM training_units"
                UpdateCommand="UPDATE training_units SET training_unit_name=@training_unit_name
                     WHERE training_unit_id=@training_unit_id"
            />
 
            <asp:GridView id="EditGrid" DataSourceID="ProductsSource" Runat="Server"
                  AutoGenerateEditButton="True"
                  DataKeyNames="training_unit_id"/>
 

The select runs fine, but when I try to do the update (hit "Edit", make a change, then hit "Update"), I get the message: Must declare variable '@training_unit_name'. I've tried uisng the UpdateParameters tag, but to no avail.

This is pretty simple. Why isn't it working?

Robert