Hello, Currently it seams that using underscore as part of a field makes it impossible to use the field in a rule. eg. public class Bean { private boolean my_boolean; } rule "Test" dialect "mvel" when b: Bean(my_boolean == true) .... When compiling the rule this results in "Unable to build constraint as 'my_boolean' is invalid" error using Drools 5.2.0.CR1 and "Unable to create Field Extractor for 'my_boolean' of '[ClassObjectType class=com.test.Bean]'" using Drools 5.1.1 Is this the expected behavior? Cheers, Samuli -- Remion Oy Etävalvontajärjestelmät liiketoiminnan Samuli Saarinen tehostamiseen gsm +358 (0)50 3560075 fax +358 (0)3 2125064 www.remion.com