[rules-users] NullPointerException when using Drools rule template

All - I tried out Drools rule template with a with a proptotype app. Drools is throwing NullPointerException as below. I would much appreciate if someone on this list can help. java.lang.NullPointerException at org.drools.template.parser.DefaultTemplateColumn.createCellCondition(DefaultTemplateColumn.java:68) at org.drools.template.parser.DefaultTemplateColumn.addCondition(DefaultTemplateColumn.java:91) at org.drools.template.parser.DefaultTemplateRuleBase.createColumnConditions(DefaultTemplateRuleBase.java:105) at org.drools.template.parser.DefaultTemplateRuleBase.createTemplateRule(DefaultTemplateRuleBase.java:98) at org.drools.template.parser.DefaultTemplateRuleBase.getDTRules(DefaultTemplateRuleBase.java:85) at org.drools.template.parser.DefaultTemplateRuleBase.<init>(DefaultTemplateRuleBase.java:64) at org.drools.template.parser.TemplateDataListener.<init>(TemplateDataListener.java:76) at org.drools.template.parser.TemplateDataListener.<init>(TemplateDataListener.java:52) at org.drools.template.ObjectDataCompiler.compile(ObjectDataCompiler.java:44) Here is my code KnowledgeBuilder kBuilder = KnowledgeBuilderFactory.newKnowledgeBuilder(); ObjectDataCompiler converter = new ObjectDataCompiler(); InputStream dis = new FileInputStream( new File( "/home/pranab/Projects/gridx/ct11_1.drl" ) ); if (null == dis){ System.out.println("null rule template stream"); return; } Collection<Map<String,Object>> paramMaps = new ArrayList<Map<String,Object>>(); Map<String,Object> params = new HashMap<String,Object>(); params.put("summerOnPeakPrimaryRate", new Integer(299)); params.put("summerOnPeakSecondaryRate", new Integer(524)); params.put("summerSemiPeakPrimaryRate", new Integer(176)); params.put("summerSemiPeakSecondaryRate", new Integer(305)); params.put("summerOffPeakPrimaryRate", new Integer(139)); params.put("summerOffPeakSecondaryRate", new Integer(243)); params.put("winterOnPeakPrimaryRate", new Integer(249)); params.put("winterOnPeakSecondaryRate", new Integer(438)); params.put("winterSemiPeakPrimaryRate", new Integer(176)); params.put("winterSemiPeakSecondaryRate", new Integer(305)); params.put("winterOffPeakPrimaryRate", new Integer(139)); params.put("winterOffPeakSecondaryRate", new Integer(243)); paramMaps.add(params); String drl = converter.compile(paramMaps, dis); Reader rdr = new StringReader( drl ); kBuilder.add( ResourceFactory.newReaderResource(rdr), ResourceType.DRL); The line in blue is throwing the exception. This code is very similar to the example code in Drools Expert guide. Best, Roger