[rules-users] org.drools.RuntimeDroolsException when inserting into Knowledge Session

I am getting the following error when trying to insert my object into ksession. I have attached my rules and java object. Please help me in debugging why this is happening. I am using java 5 and drools 5.0 thanks *error while inserting:* org.drools.RuntimeDroolsException: defaultpkg.Rule_CheckStationNumber_0Eval0Invoker@e4aea391 : java.lang.NullPointerException *rules.drl* import java.lang.*; import java.util.*; import ct.fw.rules.*; import ct.fw.utils.*; import ct.fw.rules.*; import ct.fw.logging.*; import ct.fw.pf.dbi.*; import ct.fw.pf.dao.*; import ct.fw.pf.seq.*; import ct.fw.pf.util.*; import ct.fw.pf.vo.*; import ct.fw.ex.*; import org.apache.commons.lang.*; import com.aa.gccp.domain.*; global ct.fw.rules.AssertionObject ao global ct.fw.logging.SmartLogger log function BillingRecord getRecord(AssertionObject ao) { return (BillingRecord) ao.get(0); } function void debug(String msg,SmartLogger log) { log.debug(BusinessRulesValidator.class, msg); } function void error(String msg,SmartLogger log) { log.error(BusinessRulesValidator.class, msg); System.out.println("Message from rules "+msg); } rule CheckTrue when eval(true) then System.out.println("evaluating true"); end rule CheckTrue2 when eval(true) then error("evaluating from rules2",log); end rule CheckStationNumber when eval(((getRecord(ao)).getStationNo()) == null) then error("station number should not be null",log); end *part where i load the rules and insert the facts. There is no error when loading the rules.drl. That means no parsing errors. The error happens at ksessio.insert(assertionObject).* public void assertRulesObject(AssertionObject assertionObject) throws BusinessRuleException { long current = System.currentTimeMillis(); KnowledgeBase kbase = knowledgeBasesMap.get(rulesFileName); if (kbase == null) { kbase = knowledgeBasesMap.get(rulesFileName + DRL); } if ((kbase == null) || ((current - lastRefreshedMilliseconds) > refreshTimeMilliseconds)) { if (rulesFileName.toLowerCase().indexOf(DRL) == -1) { kbase = load(rulesFileName + DRL); } else { kbase = load(rulesFileName); } lastRefreshedMilliseconds = System.currentTimeMillis(); } this.assertionObject = assertionObject; List assertionobjectslist = new ArrayList(); *// i am just doing this part just to make sure assertion object is not null and i will get some answer. this part runs fine. * if (assertionObject != null) { assertionobjectslist = assertionObject.getValidationObjects(); String StationNumber = ((BillingRecord) assertionObject.get(0)).getStationNo(); System.out.println("Station Number in assertion object is " + StationNumber); } else { System.out.println("Assertion Object is null"); } System.out.println("The number of objects in assertionobject is " + assertionobjectslist.size()); try { StatefulKnowledgeSession ksession = kbase.newStatefulKnowledgeSession(); *//the next line throws the exception* ksession.insert(assertionObject); ksession.fireAllRules(); ksession.dispose(); } catch (RuntimeDroolsException e1) { throw new BusinessRuleException(e1.getMessage()); } businessRulesErrors = assertionObject.getBusinessRulesErrors(); if (throwException) { if (!assertionObject.getBusinessRulesErrors().isEmpty()) { throw new BusinessRuleException(businessRulesErrors); } } } Any help is appreciated. thanks