[rules-users] Error in upgrading to drools 4

Hi, I have an application using drools 3.0.6. I downloaded jboss rules 4.0.2 GA and made necessary changes to the code to make it compatible to version 4.0.2. When I try to run the application now, I am getting following error. 2007-10-22 19:12:16,255 ERROR [STDERR] java.lang.NoSuchMethodError: org.antlr.runtime.DFA.unpackEncodedString(Ljava/lang/String;)[S 2007-10-22 19:12:16,255 ERROR [STDERR] at org.drools.lang.DRLParser.<clinit>(DRLParser.java:7205) 2007-10-22 19:12:16,255 ERROR [STDERR] at org.drools.compiler.DrlParser.getParser(DrlParser.java:204) 2007-10-22 19:12:16,255 ERROR [STDERR] at org.drools.compiler.DrlParser.parse(DrlParser.java:60) 2007-10-22 19:12:16,256 ERROR [STDERR] at org.drools.compiler.PackageBuilder.addPackageFromDrl(PackageBuilder.java:158) 2007-10-22 19:12:16,256 ERROR [STDERR] at com.egatematrix.ess.framework.service.remote.rules.RulesEngineInvoker.readRule(RulesEngineInvoker.java:83) 2007-10-22 19:12:16,256 ERROR [STDERR] at com.egatematrix.ess.framework.service.RuleService.doProcess(RuleService.java:294) 2007-10-22 19:12:16,256 ERROR [STDERR] at com.egatematrix.ess.framework.service.FetchFSSData.invokeRuleService(FetchFSSData.java:140) 2007-10-22 19:12:16,256 ERROR [STDERR] at com.egatematrix.ess.framework.service.FetchFSSData.triggerData(FetchFSSData.java:68) 2007-10-22 19:12:16,256 ERROR [STDERR] at com.egatematrix.ess.framework.service.FetchFSSData$1.run(FetchFSSData.java:84) 2007-10-22 19:12:16,256 ERROR [STDERR] at java.util.TimerThread.mainLoop(Timer.java:512) 2007-10-22 19:12:16,257 ERROR [STDERR] at java.util.TimerThread.run(Timer.java:462) I have antlr-runtime-3.0.jar in my classpath which came with drools 4 distribution. I don't have any other version of antlr in my classpath. Has anyone else encountered this problem? Any help will be appreciated. thanks, Prashant