add Style statement is not working after upgradation of UI5

HI Friends ,

after upgradation of sap ui5 , the addstyle statement is not working properly . it is executing perfectly . but the results are not appearing fiori launchpad .but the results are working fine from WEBIDE .

sap.ui.getCore().mainView.byId('generalInformationLabelRequestDescn').addStyleClass("mandatoryInput");

please help me.