DataGrid return selectedItems only if row.Header is selected

Question

I have a DataGrid and want to get the selected items and delete with right click option. When I select at least one cell of a row, it must delete the entire row.

When I select like in the example below:

example 1

the DataGrid.SelectedItems.Count is 0. However, if I include the row header in the selection, it works perfectly.

example 2

Does anyone have any clue about it?

Code:

private void DeleteRowSelection_Executed(object sender, System.Windows.Input.ExecutedRoutedEventArgs e)
{
         DataTable dataTable = ((DataEditor)sender).DataNode.DataTable;
         var gridCell = ((DataGridCell)e.OriginalSource);
         var parent = VisualTreeHelper.GetParent(gridCell);
         while (parent != null && parent.GetType() != typeof(DataGrid))
         {
            parent = VisualTreeHelper.GetParent(parent);
         }

         DataGrid dataGrid = (DataGrid)parent;

         try
         {
            if (dataGrid.SelectedItems.Count == 1)
            {
               int selectedIndex = dataGrid.SelectedIndex;
               var row = dataTable.Rows[selectedIndex];
               row.Delete();
            }
            else if (dataGrid.SelectedItems.Count > 1)
            {
               while (dataGrid.SelectedItems.Count >= 1)
               {
                  DataRowView drv = (DataRowView)dataGrid.SelectedItem;
                  drv.Row.Delete();
               }
            }
         }
         catch (Exception ex)
         {
            MessageBox.Show(ex.Message);
         }
 }