Conditional Style not working after compiling with JasperDesign object using java or programatically

[onlywithnik]

I am trying to add conditional style programatically with existing reort. When I compilling with jasperdesign object it wont reflect any style in PDF. But same if i first write into JRXML and again load and compiling the it will work. ( see my commented lines those line works but why not with the same object)

See below code it wont work:

JasperDesign jasDes = new JasperDesign();

            logger.info("Loading JRXML into Jasper Design: [" + rptPath + "]");
            jasDes = JRXmlLoader.load(rptPath);

            JRDesignGroup jrDesignGroup = new JRDesignGroup();
            jrDesignGroup.setName("pagebreak");
            JRExpression jrExpression = new JRDesignExpression("$F{pgno}");
            jrDesignGroup.setExpression(jrExpression);
            jrDesignGroup.setStartNewPage(true);
            jasDes.addGroup(jrDesignGroup);

            JRDesignStyle designStyle = new JRDesignStyle();
            designStyle.setName("Table_TR");
            designStyle.setMode(ModeEnum.OPAQUE);
            designStyle.setBackcolor(null);
            jasDes.addStyle(designStyle);
            
            jrExpression = new JRDesignExpression("$F{reclvl}.equals("B")");
            JRDesignConditionalStyle conditionalStyle = new JRDesignConditionalStyle();
            conditionalStyle.setBackcolor(Color.decode("#BD5553"));
            conditionalStyle.setMode(ModeEnum.OPAQUE);
            conditionalStyle.setConditionExpression(jrExpression);
            designStyle.addConditionalStyle(conditionalStyle);

//            String temp = JRXmlWriter.writeReport(jasDes, JRXmlTemplateWriter.DEFAULT_ENCODING);

//         JasperReport jasperReport = JasperCompileManager.compileReport(new ByteArrayInputStream(temp.getBytes());
            JasperReport jasperReport = JasperCompileManager.compileReport(jasDes);
            JasperPrint jasperPrint = JasperFillManager.fillReport(jasperReport, parameters, conn);
            JasperExportManager.exportReportToPdfFile(jasperPrint, exportPath);