Assertion error

<p>HI I am getting following error while canceling task. SEVERE [org.eclipse.birt.report.engine.api.impl.RunTask.doRun] : Error happened while running the report.java.lang.AssertionError at org.eclipse.birt.data.engine.odi.AggrHolderManager.doSave(AggrHolderManager.java:99) at org.eclipse.birt.data.engine.executor.transform.CachedResultSet.doSave(CachedResultSet.java:352) at org.eclipse.birt.data.engine.impl.document.RDSaveUtil.saveForGeneration(RDSaveUtil.java:96) at org.eclipse.birt.data.engine.impl.document.RDSaveUtil.saveResultIterator(RDSaveUtil.java:63) at org.eclipse.birt.data.engine.impl.document.RDSave.saveResultIterator(RDSave.java:237) at org.eclipse.birt.data.engine.impl.ResultIterator$RDSaveHelper.doSaveBasic(ResultIterator.java:1264) at org.eclipse.birt.data.engine.impl.ResultIterator$RDSaveHelper.access$0(ResultIterator.java:1256) at org.eclipse.birt.data.engine.impl.ResultIterator.prepareCurrentRow(ResultIterator.java:729) at org.eclipse.birt.data.engine.impl.ResultIterator.<init>(ResultIterator.java:166) at org.eclipse.birt.data.engine.impl.QueryResults.getResultIterator(QueryResults.java:208) at org.eclipse.birt.report.engine.data.dte.QueryResultSet.<init>(QueryResultSet.java:98) at org.eclipse.birt.report.engine.data.dte.DteDataEngine.doExecuteQuery(DteDataEngine.java:168) at org.eclipse.birt.report.engine.data.dte.DataGenerationEngine.doExecuteQuery(DataGenerationEngine.java:80) at org.eclipse.birt.report.engine.data.dte.AbstractDataEngine.execute(AbstractDataEngine.java:265) at org.eclipse.birt.report.engine.executor.ExecutionContext.executeQuery(ExecutionContext.java:1897) at org.eclipse.birt.report.engine.executor.QueryItemExecutor.executeQuery(QueryItemExecutor.java:80) at org.eclipse.birt.report.engine.executor.TableItemExecutor.execute(TableItemExecutor.java:62) at org.eclipse.birt.report.engine.internal.executor.wrap.WrappedReportItemExecutor.execute(WrappedReportItemExecutor.java:46) at org.eclipse.birt.report.engine.internal.executor.emitter.ReportItemEmitterExecutor.execute(ReportItemEmitterExecutor.java:46) at org.eclipse.birt.report.engine.internal.executor.dup.SuppressDuplicateItemExecutor.execute(SuppressDuplicateItemExecutor.java:43) at org.eclipse.birt.report.engine.internal.executor.wrap.WrappedReportItemExecutor.execute(WrappedReportItemExecutor.java:46) at org.eclipse.birt.report.engine.internal.executor.l18n.LocalizedReportItemExecutor.execute(LocalizedReportItemExecutor.java:34) at org.eclipse.birt.report.engine.layout.html.HTMLBlockStackingLM.layoutNodes(HTMLBlockStackingLM.java:65) at org.eclipse.birt.report.engine.layout.html.HTMLPageLM.layout(HTMLPageLM.java:92) at org.eclipse.birt.report.engine.layout.html.HTMLReportLayoutEngine.layout(HTMLReportLayoutEngine.java:100) at org.eclipse.birt.report.engine.presentation.ReportDocumentBuilder.build(ReportDocumentBuilder.java:249) at org.eclipse.birt.report.engine.api.impl.RunTask.doRun(RunTask.java:260) at org.eclipse.birt.report.engine.api.impl.RunTask.run(RunTask.java:85)</p>