I'm having the same problem.

Here is my code (svc is my RIA service):

  private void LoadData()
        {
            svc.Load(svc.GetActiveMedicalWeightRecordsQuery(),
                result =>
                {
                    dgWeight.ItemsSource = svc.MedicalWeightRecords;
                }, null);
               
        }

HERE IS my xaml

 <igGrid:XamGrid HorizontalAlignment="Left" Name="dgWeight" VerticalAlignment="Top" AutoGenerateColumns="False" IsAlternateRowsEnabled="True" IsEnabled="False" ColumnWidth="*">
                <igGrid:XamGrid.AddNewRowSettings>
                    <igGrid:AddNewRowSettings AllowAddNewRow="Top" IsMouseActionEditingEnabled="SingleClick" ></igGrid:AddNewRowSettings>
                </igGrid:XamGrid.AddNewRowSettings>
                <igGrid:XamGrid.EditingSettings>
                    <igGrid:EditingSettings AllowEditing="Row" />
                </igGrid:XamGrid.EditingSettings>
                <igGrid:XamGrid.SummaryRowSettings>
                    <igGrid:SummaryRowSettings AllowSummaryRow="None" />
                </igGrid:XamGrid.SummaryRowSettings>
                <igGrid:XamGrid.Columns>
                    <igGrid:TemplateColumn Key="DateRecorded" HeaderText="Date Recorded">
                        <igGrid:TemplateColumn.ItemTemplate>
                            <DataTemplate>
                                <TextBlock Text="{Binding DateRecorded, Mode=TwoWay}"></TextBlock>
                            </DataTemplate>
                        </igGrid:TemplateColumn.ItemTemplate>
                        <igGrid:TemplateColumn.EditorTemplate>
                            <DataTemplate>
                                <sdk:DatePicker SelectedDate="{Binding DateRecorded, Mode=TwoWay}" />
                            </DataTemplate>
                        </igGrid:TemplateColumn.EditorTemplate>
                    </igGrid:TemplateColumn>
                    <igGrid:TemplateColumn Key="Weight">
                        <igGrid:TemplateColumn.ItemTemplate>
                            <DataTemplate>
                                <TextBlock Text="{Binding Weight, Mode=TwoWay}"></TextBlock>
                            </DataTemplate>
                        </igGrid:TemplateColumn.ItemTemplate>
                        <igGrid:TemplateColumn.EditorTemplate>
                            <DataTemplate>
                                <TextBox Text="{Binding Weight, Mode=TwoWay}"></TextBox>
                            </DataTemplate>
                        </igGrid:TemplateColumn.EditorTemplate>
                    </igGrid:TemplateColumn>
                </igGrid:XamGrid.Columns>
            </igGrid:XamGrid>