Unable to get the UWL Service from CE7.2

I am trying to get UWL service from NWCE 7.2 in EJB. But getting the below exception.

The code i am using is as below.

Properties env = new Properties();            env.put(InitialContext.INITIAL_CONTEXT_FACTORY, "com.sapportals.portal.prt.registry.PortalRegistryFactory");            // create initial context            InitialContext ctx = new InitialContext(env);            // retrieve UWL service            IUWLService uwlService = (IUWLService) ctx.lookup("/broker/services/" + IUWLService.ALIAS_KEY);

I have created External Library DC with UWL API's and referenced it to EJB Project. I have directly downloaded the jar files from the server.

I am getting the same error even when tried to get UWL service in WDJ application with the below code.

IUWLService uwlService = (IUWLService) WDPortalUtils.getServiceReference( IUWLService.ALIAS_KEY);

Any help and suggestions would be appreciated.