How to export the grid with customized background to excel in WinForms GridGroupingControl?

private void bt_export_Click(object sender, System.EventArgs e)
{
   SaveFileDialog saveFileDialog = new SaveFileDialog();
   saveFileDialog.Filter = "Files(*.XLS)|*.XLS";
   saveFileDialog.AddExtension = true;
   saveFileDialog.DefaultExt = ".XLS";
   if(saveFileDialog.ShowDialog() == DialogResult.OK && saveFileDialog.CheckPathExists)
   {
      GroupingGridExcelConverterControl converter = new GroupingGridExcelConverterControl();
      //ExportStyle
      converter.ExportBorders = true;
      //set the backcolor of the header
      converter.HeaderBackColor = Color.Aqua;
      //set the backcolor of the caption
      converter.CaptionBackColor = Color.MistyRose;
      converter.ExportPreviewRows = true;
      //export the plus/minus icons
      converter.ExportGroupPlusMinus = true;
      converter.ExportRecordPlusMinus = true;
      ConverterOptions options = ConverterOptions.Default;
      converter.GroupingGridToExcel(this.gridGroupingControl1, saveFileDialog.FileName, options);
      converter.Dispose();
      if(MessageBox.Show("Do you wish to open the xls file now?", "Export to Excel", MessageBoxButtons.YesNo, MessageBoxIcon.Question) == DialogResult.Yes)
      {
         System.Diagnostics.Process proc = new System.Diagnostics.Process();
         proc.StartInfo.FileName = saveFileDialog.FileName;
         proc.Start();
      }
   }
}

Private Sub bt_export_Click(ByVal sender As Object, ByVal e As System.EventArgs)
   Dim saveFileDialog As New SaveFileDialog()
   saveFileDialog.Filter = "Files(*.XLS)|*.XLS"
   saveFileDialog.AddExtension = True
   saveFileDialog.DefaultExt = ".XLS"
   If saveFileDialog.ShowDialog() = DialogResult.OK AndAlso saveFileDialog.CheckPathExists Then
     Dim converter As New GroupingGridExcelConverterControl()
     'ExportStyle
     converter.ExportBorders = True
     'set the backcolor of the header
     converter.HeaderBackColor = Color.Aqua
     'set the backcolor of the caption
     converter.CaptionBackColor = Color.MistyRose
     converter.ExportPreviewRows = True
     'export the plus/minus icons
     converter.ExportGroupPlusMinus = True
     converter.ExportRecordPlusMinus = True
     Dim options As ConverterOptions = ConverterOptions.Default
     converter.GroupingGridToExcel(Me.gridGroupingControl1, saveFileDialog.FileName, options)
     converter.Dispose()
     If MessageBox.Show("Do you wish to open the xls file now?", "Export to Excel", MessageBoxButtons.YesNo, MessageBoxIcon.Question) = DialogResult.Yes Then
        Dim proc As New System.Diagnostics.Process()
        proc.StartInfo.FileName = saveFileDialog.FileName
        proc.Start()
     End If
  End If
End Sub