Hi Cilambarasan,
The service you are using looks fine.
The same can be confirmed from the API referrence guide of Report Engine SDks for 4.0.
Refer to the ReportEngines class.
You will find the below mechanism.
ReportEngines repEngines = (ReportEngines)enterpriseSession.getService("ReportEngines");
ReportEngine wiRepEngine = repEngines.getService(ReportEngines.ReportEngineType.WI_REPORT_ENGINE);
However said that, below are the options you can look at.
1. Confirm whether the web intelligence processing servers in your environment are up and running. Also make sure that your SDK app is able to communicate with the web intelligence processing servers.
2. Confirm that you are using the jars from the current version in your applications classpath.
For testing purpose include all the jars from java/lib and java/lib/external in to your applications classpath to check whether it resolves your issue
Thanks,
Prithvi