How to bind the combo box inside the DataGrid.RowDetailsTemplate

Question

Hi,

    I have a data grid which has RowDetails.Template. In that i have another grid which will have the combo box that will bind data from a service. But that combo box is not binded and it is not populating. Please find the sample code below and help me out.

xaml:
===========

 <data:DataGrid x:Name="dgSilverligh" Grid.Row="2" Grid.Column="0" Grid.ColumnSpan="3" AutoGenerateColumns="False"  Foreground="Black"   RowHeight="22"  Margin="5,3,5,0" 
            ItemsSource="{Binding}"  VerticalAlignment="Stretch" HorizontalAlignment="Stretch" MinHeight="250" >
     <data:DataGrid.Columns>
        <data:DataGridTemplateColumn Header="First Name">
            <data:DataGridTemplateColumn.CellTemplate>
            <DataTemplate>
            <HyperlinkButton x:Name="hyberID" Content="{Binding FirstName, Mode=TwoWay}" Width="150" Height="25"  Cursor="Hand" FontWeight="SemiBold"  Foreground="RoyalBlue" VerticalAlignment="Center"  ></HyperlinkButton>
            </DataTemplate>
            </data:DataGridTemplateColumn.CellTemplate>
            </data:DataGridTemplateColumn>

</data:DataGrid.Columns>


<data:DataGrid.RowDetailsTemplate >
                <DataTemplate>
                    <StackPanel Background="LightBlue">
                        <StackPanel Orientation="Horizontal">
                            <TextBlock Text="This item has details." />
                        </StackPanel>
                        <StackPanel Orientation="Horizontal" >
                            <data:DataGrid x:Name="dgSilverligh_Inner"  VerticalAlignment="Stretch" HorizontalAlignment="Stretch" LoadingRow="dgSilverligh_Inner_LoadingRow" Width="100" >
                                <data:DataGrid.Columns>
                                    <data:DataGridTemplateColumn Width="60">
                                        <data:DataGridTemplateColumn.CellEditingTemplate>
                                            <DataTemplate>
                                                <ComboBox x:Name="cmb1" Loaded="cmb1_Loaded"  DisplayMemberPath="Name"  VerticalAlignment="Center" HorizontalAlignment="Left" Width="60"></ComboBox>
                                            </DataTemplate>
                                        </data:DataGridTemplateColumn.CellEditingTemplate>
                                    </data:DataGridTemplateColumn>
                                </data:DataGrid.Columns>
                            </data:DataGrid>
                        </StackPanel>
                    </StackPanel>
                </DataTemplate>
            </data:DataGrid.RowDetailsTemplate>


xaml.cs
===========

  private void cmb1Loaded(object sender, RoutedEventArgs e)
        {
            ComboBox ComboBox1 = new ComboBox();
            ComboBox1.ItemsSource = objStage;
        }

 private void dgSilverligh_Inner_LoadingRow(object sender, DataGridRowEventArgs e)
        {
            DataGrid dg = (DataGrid)sender;
            ComboBox cmb1 = dg.Columns[0].GetCellContent(e.Row) as ComboBox;
            cmb1.ItemsSource = objStage;
            cmb1.SelectedIndex = 0;
}

Thanks,
Vijay