New Post: Conditional Format is not work for XSSFWorkbook

HSSFWorkbook wk = new HSSFWorkbook();  // 2003
//XSSFWorkbook wk = new XSSFWorkbook();    // 2007

ISheet sheet = wk.CreateSheet("Report");
ISheetConditionalFormatting ConditionalFormatting = sheet.SheetConditionalFormatting;

IConditionalFormattingRule LessThan1_33 = ConditionalFormatting.CreateConditionalFormattingRule(ComparisonOperator.LessThan, "1.33", null);
IPatternFormatting patternFmt1 = LessThan1_33.CreatePatternFormatting();
patternFmt1.FillBackgroundColor = NPOI.HSSF.Util.HSSFColor.Red.Index;
CellRangeAddress[] regions1 = { new CellRangeAddress(1, Designators.Count, 8, 8) };
ConditionalFormatting.AddConditionalFormatting(regions1, LessThan1_33);