ValidatorAction throws NullPointerException w/ Struts 1.2.7

[biguniverse]

Anyone have a clue why the latest version of Struts causes this? It was working fine with my previous version of Struts but I wanted to the ValidWhen functionality, so I upgraded.

[org.apache.commons.validator.ValidatorAction] - <Unhandled exception thrown during validation: null>
java.lang.NullPointerException
at org.apache.struts.validator.Resources.getMessageRe sources(Resources.java:127)
at org.apache.struts.validator.Resources.getActionMes sage(Resources.java:349)
at org.apache.struts.validator.FieldChecks.validateRe quired(FieldChecks.java:94)

[biguniverse]

P.S. Not sure if this is related to the above problem but I just found this on http://struts.apache.org/userGuide/dev_validator.html

Note that since Struts 1.1, you must explicitly define your message resource in any module that is going to use the Validator, due to a problem accessing the top-level resource. This only effects applications which are using modules.