[rules-users] Drools 4.0.7, Java 5 which mvel version should I use

Hello, I just started to use Enums in my rules and I got following Exception during execution of the rule (compilation of rules is OK) [...] Caused by: org.mvel.PropertyAccessException: unable to resolve property: unable to resolve token: MetaType.cover MetaType is an Enum... I know my error may not be related with the version of mvel but I noticed I'm using mvel-1.3.1-java1.4.jar which looks like a version for java 1.4, so my question is what version of mvel should I use? I know I have to use a 1.3.* version, but I've read somewhere 1.3.13 won't initialise, so I guess I should use 1.3.12? Thanks for your help -Patrick