Hi! I want to program the following drl rule in xml: rule "average calculation" no-loop true when _i : Instance() _average : Double() from accumulate(accInst: Instance(), average(accInst.value("tend"))) eval(_average < 20000) then _i.setValue("tend",2000); end For it, I have implemented the following xml file: <?xml version="1.0" encoding="UTF-8"?> <package name="org.prophet.fuzzy" xmlns="http://drools.org/drools-4.0" xmlns:xs="http://www.w3.org/2001/XMLSchema-instance" xs:schemaLocation="http://drools.org/drools-4.0 drools-4.0.xsd"> <import name="weka.core.*"/> <import name="org.prophet.gui.docking.*"/> <import name="org.prophet.persistence.*"/> <import name="org.prophet.persistence.hibernate.*"/> <import name="org.prophet.rules.*"/> <import name="org.prophet.*"/> <rule name="Rule1"> <rule-attribute name="no-loop" value="true"/> <lhs> <pattern identifier="_i" object-type="Instance"/> <pattern identifier="_average" object-type="Double"> <from> <accumulate> <pattern identifier="accInst" object-type="Instance"/> <external-function evaluator="average" expression="accInst.value(&quot;tend&quot;)"/> </accumulate> </from> </pattern> <eval>_average &lt; 20000.0</eval> </lhs> <rhs> _i.setValue("tend", 2000.0); manageRuleFired("Rule1", null, _i); modify(_i);</rhs> </rule> </package> And I have the following error when reading the rule package: org.drools.rule.InvalidRulePackage: Rule Compilation error _average cannot be resolved _i cannot be resolved _i cannot be resolved _i__Handle__ cannot be resolved _i cannot be resolved I also have tried to replace the xml identifier <pattern> by <column> with no result. Can you help me, please? -- View this message in context: http://www.nabble.com/accumulate-funtion-in-xml-tf4526879.html#a12916380 Sent from the drools - user mailing list archive at Nabble.com.