Try not to separate the message tag and CDATA portion. The parser might create a text node enclosing the CDATA if it sees any space, and xwork just reads the first node (therefore, an empty text). Example:-

<field name="password">
  <field-validator type="requiredstring">
   <message><![CDATA[ Debe proporcionar una contraseña para el usuario. ]]></message>
  </field-validator>
</field>

Note: there's no spacing in the following line

<message><![CDATA[ ...]]></message>

Contributor: Ruben