Why var can not be used in the when clause? I tried to use it in then clause such as modify ($d) {var = "d"}; it just worked well. Is var a keyword in drools or mvel? I didn't find it anywhere both in drools export doc and mvel guide. Following is the content of my drl file: package test declare Dd @propertyReactive var : String age : Integer end rule "Rule A" dialect "mvel" salience 0 no-loop when $d:Dd(var == "a") then modify ($d) {age = 3}; end In the eclipse editor, it just shows an error marker before line $d:Dd(var == "a"): BuildError: Unable to Analyse Expression var == "a": [Error: unexpected end of statement] [Near : {... var == "a" ....}] ^ [Line: 14, Column: 0] And when invoke the rule, it just threw following exception: java.lang.RuntimeException: Error while creating KieBase[Message [id=1, level=ERROR, path=rules/Sample.drl, line=14, column=0 text=Unable to Analyse Expression var == "a": [Error: unexpected end of statement] [Near : {... var == "a" ....}] ^ [Line: 14, Column: 0]]] at org.drools.compiler.kie.builder.impl.KieContainerImpl.getKieBase(KieContainerImpl.java:176) at org.drools.compiler.kie.builder.impl.KieContainerImpl.newKieSession(KieContainerImpl.java:315) at org.drools.compiler.kie.builder.impl.KieContainerImpl.newKieSession(KieContainerImpl.java:290) at com.sample.DroolsTest.main(DroolsTest.java:18) I really appreciate any help you can provide. -- View this message in context: http://drools.46999.n3.nabble.com/BuildError-Unable-to-Analyse-Expression... Sent from the Drools: User forum mailing list archive at Nabble.com. _______________________________________________ rules-users mailing list rules-users(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users