The tag should display sting from corresponding message bundle.

Example: we have in struts-config.xml following declaration:
<message-resources key="resource" parameter="resource"/>
in file resource.properties:
badlogin=Your password or login is incorrect!

JSP:
<bean:message bundle="resource" key="badlogin"/>

Tag should dispay "Your password or login is incorrect!", but it is shown as unknown tag.

Look at attached screenshot with examples of unrecognized tags.

Test project attached