Silverlight 3 + Проблем с ангажиране на данни за услугите на RIA

Работя върху приложение Silverlight 3 с RIA Services. Пускам приложението, но по някаква причина то само чете данни, не извършва промени.

Повечето от онлайн примерите, които съм виждал, използват Linq2Entities; ние използваме Linq2SQL (нашият модел на данни е доста добър такъв, какъвто е, без абстракция.)

Ето фрагмент от услугата:

[EnableClientAccess]
public class FooService : LinqToSqlDomainService<FooDataContext>
{
    [RequiresAuthentication()]
    public IQueryable<UserProfile> GetUserProfiles()
    {
        return this.Context.UserProfiles;
    }

    [RequiresAuthentication()]
    public void InsertUserProfile(UserProfile profile)
    {
        this.Context.UserProfiles.InsertOnSubmit(profile);
    }

    [RequiresAuthentication()]
    public void UpdateUserProfile(UserProfile currentProfile)
    {
        this.Context.UserProfiles.Attach(currentProfile, true);
    }

    [RequiresAuthentication()]
    public void DeleteUserProfile(UserProfile profile)
    {
        this.Context.UserProfiles.Attach(profile, profile);
        this.Context.UserProfiles.DeleteOnSubmit(profile);
    }
}

Ето фрагмент от XAML, който използвам:

<dataControls:DataForm x:Name="_profileForm" AutoGenerateFields="False" CommandButtonsVisibility="Commit" AutoEdit="True" >
                <dataControls:DataForm.EditTemplate>
                    <DataTemplate>
                        <StackPanel Orientation="Vertical">
                            <dataControls:DataField Label="Username">
                                <TextBox Text="{Binding UserName, Mode=TwoWay}" />
                            </dataControls:DataField>

                            <dataControls:DataField Label="First Name">
                                <TextBox Text="{Binding FirstName, Mode=TwoWay}" />
                            </dataControls:DataField>

                            <dataControls:DataField Label="Last Name">
                                <TextBox Text="{Binding LastName, Mode=TwoWay}" />
                            </dataControls:DataField>

                            <dataControls:DataField Label="Password">
                                <PasswordBox Password="{Binding Password, Mode=TwoWay}"/>
                            </dataControls:DataField>

                            <!-- [Snip] -->

                            </dataControls:DataField>
                        </StackPanel>
                    </DataTemplate>
                </dataControls:DataForm.EditTemplate>
            </dataControls:DataForm>

И ето фрагмент от страницата Silverlight:

public partial class Profile : Page
{
    private FooContext _dataContext;

    public Profile()
    {
        InitializeComponent();
        this._dataContext = new FooContext();
    }

    protected override void OnNavigatedTo(NavigationEventArgs e)
    {
        LoadOperation<UserProfile> loadOperation = this._dataContext.Load<UserProfile>(this._dataContext.GetUserProfilesQuery());
        loadOperation.Completed += new EventHandler(this.LoadOperation_Completed);
    }

    private void LoadOperation_Completed(object sender, EventArgs e)
    {
        // Bind the RIA data to the controls
        LoadOperation<UserProfile> loadOperation = sender as LoadOperation<UserProfile>;
        this._profileForm.EditEnded += new EventHandler<DataFormEditEndedEventArgs>(ProfileForm_EditEnded);
        this._profileForm.ItemsSource = loadOperation.Entities;
        this._profileForm.CurrentIndex = 0;
    }

    private void ProfileForm_EditEnded(object sender, DataFormEditEndedEventArgs e)
    {
        this._dataContext.SubmitChanges();
    }