TabStrip issue

Hi Expert,

TabStrip is not displaying.Can any one tell me where am doing mistake.

Code:

var otabstrip = new sap.ui.commons.TabStrip();

           otabstrip.setHeight("500px");

           otabstrip.setWidth("400px");

           var otab1 = new sap.ui.commons.Tab({ text : "Input"});

           var otab2 = new sap.ui.commons.Tab({ text : "OutPut"});

           var otab3 = new sap.ui.commons.Tab({ text : "Display"});

           var otab4 = new sap.ui.commons.Tab({ text : "Edite"});

           otab1.addContent(ocomboBox);

           otab2.addContent(odrp);

           otab3.addContent(oRbtgrp);

           otab4.addContent(obox);

           otabstrip.addTab(otab1);

           otabstrip.addTab(otab2);

           otabstrip.addTab(otab3);

           otabstrip.addTab(otab4);

           otabstrip.placeAt("content");

Regards,

SAM