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.

&#91;org.apache.commons.validator.ValidatorAction&#93; - <Unhandled exception thrown during validation&#58; null>
java.lang.NullPointerException
	at org.apache.struts.validator.Resources.getMessageResources&#40;Resources.java&#58;127&#41;
	at org.apache.struts.validator.Resources.getActionMessage&#40;Resources.java&#58;349&#41;
	at org.apache.struts.validator.FieldChecks.validateRequired&#40;FieldChecks.java&#58;94&#41;

[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.