Please Double Check your classpath libraries, It's with 100% sure some classpath issues. On Aug 17, 2007, at 1:53 PM, Scott Reed wrote: >> Exception in thread "main" java.lang.NoSuchMethodError: >> org.antlr.runtime.DFA.unpackEncodedString(Ljava/lang/String;)[S >> at org.drools.lang.DRLParser.<clinit>(DRLParser.java:7223)