Datagrid row height is not collapsing when collapsing the content in that row

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C#

Silverlight

This is my XAML page

<data:DataGridTemplateColumn Width="*">
	<data:DataGridTemplateColumn.CellTemplate>
		<DataTemplate>
			<Border  BorderThickness="0"
					 BorderBrush="Gray"
					 Height="Auto">
				<Grid Margin="0,0,0,20">
					<Grid.ColumnDefinitions>
						<ColumnDefinition Width="0" />
						<ColumnDefinition Width="*" />
						<ColumnDefinition Width="Auto"
										  MaxWidth="60" />
					</Grid.ColumnDefinitions>

					<Grid.RowDefinitions>
						<RowDefinition Height="Auto" />
					</Grid.RowDefinitions>

					<HyperLinkButton F>
						<Grid x:Name="grdFAQs"
							  Horiz>
							<Grid.ColumnDefinitions>
								<ColumnDefinition Width="10" />
								<ColumnDefinition Width="*" />
							</Grid.ColumnDefinitions>
							<Grid.RowDefinitions>
								<RowDefinition Height="20" />
								<RowDefinition Height="20" />
								<RowDefinition Height="Auto" />
							</Grid.RowDefinitions>
							<TextBlock x:Name="txtbAutogeneratedID"
									   Visibility="Collapsed" />
							<Image Source="../Images/Minimize1.png"
								   Margin="0,0,4,0"
								   Tag="Mininmum"
								   Visibility="Collapsed"
								   Grid.Row="0"
								   Grid.Column="0"
								   x:Name="imgminimize"
								   Height="10"
								   Width="10"
								   VerticalAlignment="Center"
								   ToolTipService.ToolTip="{Binding minimise,Source={StaticResource resourceFile}}"
								   Horiz/>
							<Image Source="../Images/add1.png"
								   x:Name="imgmaxmize"
								   Height="10"
								   Width="10"
								   Grid.Row="0"
								   Grid.Column="0"
								   Margin="0,0,0,0"
								   ToolTipService.ToolTip="{Binding maximise,Source={StaticResource resourceFile}}"
								   VerticalAlignment="Center"
								   Horiz/>

							<TextBlock Margin="3,0,0,0"
									   Horiz/>

							<TextBlock Margin="3,0,0,0"
									   Horiz/>

							<TextBlock  Text="{Binding FAQ_ANSWER}"
										Visibility="Collapsed"
										TextWrapping="Wrap"
										x:Name="txtAnswer"
										Margin="3,10,0,0"
										VerticalAlignment="Top"
										Foreground='Black'
										Style='{StaticResource TitleStyle2}'
										Horiz/>

						</Grid>

					</HyperLinkButton>


					<StackPanel Orientation="Horizontal"
								Grid.Row="0"
								Grid.Column="2"
								Margin="0,3,0,0">

						<HyperLinkButton  Height="20"
								          Margin="0,0,0,0"
								          Horiz>
							<Image  Source="../Images/documents_folder-48.png"
									Height="22"
									Width="18" />
						</HyperLinkButton>
						<HyperLinkButton Height="20"
                                         Horiz>
							<Image  Source="../Images/video.png"
									Margin="8,0,0,0"
									Height="40"
									Width="30" />
						</HyperLinkButton>
						<HyperLinkButton Height="30"
                                         Horiz>
							<Image  Source="../Images/appbar.link.png"
									Margin="2,0,0,0"
									Height="50"
									Width="30" />
						</HyperLinkButton>

					</StackPanel>

				</Grid>
			</Border>
		</DataTemplate>
	</data:DataGridTemplateColumn.CellTemplate>
</data:DataGridTemplateColumn>

And the code behind

public void hlnkbtnminimize_Click(object sender, RoutedEventArgs e)
{
    var ctr = e.OriginalSource as HyperlinkButton;
    DependencyObject dep = (DependencyObject)e.OriginalSource;
    if (ctr != null)
    {
        Image objminImg = (Image)(ctr.FindName("imgminimize"));
        Image objmaxImg = (Image)(ctr.FindName("imgmaxmize"));
        TextBlock objAnswer = (TextBlock)(ctr.FindName("txtAnswer"));
        TextBlock objSerialNo = (TextBlock)(ctr.FindName("txtbAutogeneratedID"));
        objAutogeneratedSerialNo =Convert.ToInt32(objSerialNo.Text);
        int serialNo = (objAutogeneratedSerialNo) ;
        objchk=Convert.ToString(ctr.Tag);
        if (objminImg.Visibility == Visibility.Visible)
        {
            //  GVMarketList.RowHeight= 30;
                //  ctr.Height = 40;
                //objAnswer.Height = 0;

                objminImg.Visibility = Visibility.Collapsed;
                objmaxImg.Visibility = Visibility.Visible;
                // objAnswer.Visibility = Visibility.Collapsed;
                DataGridRow row = (DataGridRow)dep;
                row.DetailsVisibility = Visibility.Collapsed;
                if (objAutogeneratedSerialNo == serialNo)
                {
                    GVMarketList.RowDetailsVisibilityMode = DataGridRowDetailsVisibilityMode.Collapsed;
                }
        }
        else
        {
            GVMarketList.RowHeight = double.NaN;
            objAnswer.Height = double.NaN;
            objmaxImg.Visibility = Visibility.Collapsed;
            objminImg.Visibility = Visibility.Visible;
            objAnswer.Visibility = Visibility.Visible;
                       
            //stkpnlvideo.Visibility = Visibility.Visible;
                         
        }
    }
}

I tried with everthing but not able to collapse the height of the row when collpasing the content in it.

You can Find the image links here
http://imagebin.ca/v/1bI9yobAzd4E[^]

[^]


Any help plz....