XML : TextBlock in c# get an empty value in RowEditEnding in datagrid

I use RowEditEnding event in datagrid to get updated row and update my database in return

      private void OnUpdateOrInsertItem(object sender,DataGridRowEditEndingEventArgs e)      {          DataGridRow row1 = e.Row;            int row_index = ((DataGrid)sender).ItemContainerGenerator.IndexFromContainer(row1);          int numberOfColumns = ((DataGrid)sender).Columns.Count;          DataGridCell RowColumn = ((DataGrid)sender).Columns[1].GetCellContent(row1).Parent as DataGridCell;          string CellValue = ((TextBlock)RowColumn.Content).Text;          MessageBox.Show(CellValue);      }    

but when I change cell which I print it in messageBox ,it returns an empty value on messageBox. I think the problem related to threads this is my xml code

  <Grid>      <DataGrid x:Name="datagrid1" AutoGenerateColumns="true" HorizontalAlignment="Left" Margin="0,55,0,0" VerticalAlignment="Top" Height="248" Width="672"  RowEditEnding="OnUpdateOrInsertItem" PreviewKeyDown="OnDeleteItem"/>      <Button Content="Show Database" HorizontalAlignment="Left" Margin="54,10,0,0" VerticalAlignment="Top" Width="98" RenderTransformOrigin="-0.193,-13.506" Height="29" Click="Button_Click_1"/>      <ComboBox x:Name="comboBox1" SelectedIndex="0" HorizontalAlignment="Left" Margin="469,17,0,0" VerticalAlignment="Top" Width="120" Loaded="ComboBox_Loaded"      SelectionChanged="ComboBox_SelectionChanged"/>  </Grid>    

how can I solve this problem or if there another way to get updated row in RowEditEnding event ?