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>

I'm facing to the problem if I assign itemsource from code the grid can't perform action of adding or deleting the system will throw exception.

My code:

_eBiz4DSys = new eBiz4DSysContext();

this.xamGrid1.ItemsSource = _eBiz4DSys.SYS_Screens;

 _eBiz4DSys.Load(_eBiz4DSys.GetSYS_ScreenQuery()); 

if I change  _eBiz4DSys.SYS_Screens into  _eBiz4DSys.SYS_Screens.ToList() xamgrid can delete or add row but didn't effect to Entity even I call submitchange as your suggested.

Thanks

With regard to the AddNewRow functionality of the grid it is only required to bind the itemsource to an object that implements IList interface. If you need to commit any changes made to the datasource than you will have to use the SubmitChanges method of the DomainDataSource. The RowAdded event is a good place to execute this method.

If I change

dgWeight.ItemsSource = svc.MedicalWeightRecords;

to

dgWeight.ItemsSource = svc.MedicalWeightRecords.ToList();

then I am able to add a row to the grid visually at least, but it doesn't get committed back to svc.MedicalWeightRecords.