Getting DPR-ERR-2056 while running a RI report with the option of Run with .csv format

I am getting an error when I run the RI report with the format as .csv or excel. But it runs fine with the HTML format. I require a .csv format or an excel version to learn and correct my reports. Can anyone help?

The error details are as below.

DPR-ERR-2056 The Report Server is not responding. Handler trace back: [the_dispatcher] com.cognos.pogo.handlers.performance.PerformanceIndicationHandler [the_dispatcher] com.cognos.pogo.handlers.logic.ChainHandler [service_lookup] com.cognos.pogo.handlers.engine.ServiceLookupHandler [load_balancer] com.cognos.pogo.handlers.logic.ChainHandler [lb_forwarder] com.cognos.p2plb.clerver.LoadBalanceHandler [batchreportservicechain] com.cognos.pogo.handlers.logic.ChainHandler [warptask_with_authenticate] com.cognos.pogo.handlers.logic.ChainHandler [do_batch_warp] com.cognos.pogo.handlers.logic.ChainHandler [warptaskmtaChain] com.cognos.pogo.handlers.logic.ChainHandler [warptaskmta] com.cognos.pogo.reportservice.BatchReportServerHandler

Thanks

Dhanya