The debug modus gives you the ability to see what data are available in Hashmap. e.g:

context=/jet-examples-webapp
message.errors.footer=</UL></FONT>
message.errors.suffix=</LI>
message.errors.header=<FONT color="red"><UL>
message.errors.prefix=<LI>
message.infos.footer=</UL></FONT>
message.infos.suffix=</LI>
message.infos.prefix=<LI>
message.infos.header=<FONT color="blue"><UL>
message.helloworld.txt1=Hello World!
message.error.creditcard=
message.error.byte=
message.error.maxlength=Field {0} is greater than {1} characters
message.error.required=The field {0} is required
message.error.doublerange=
message.error.int=The field {0} is not an int
message.error.shortrange=
message.error.date=
message.error.double=
message.error.floatrange=
message.error.longrange=
message.error.intrange=
message.error.byterange=
message.error.float=
message.error.email=
message.error.empty=The field {0} is not empty
message.error.minlength=Field {0} is lower than {1} characters
message.warns.footer=</UL></FONT>
message.warns.suffix=</LI>
message.warns.prefix=<LI>
message.warns.header=<FONT color="yellow"><UL>
newform=<form id=...

export CLASSPATH=
<source directory of property file>:
/jet.jar:
/jet-examples.jar:
/jakarta-tomcat-5.5.7/common/lib/servlet-api.jar:
/WEB-INF/lib/freemarker.jar:
/WEB-INF/lib/ehcache-1.1.jar:
/WEB-INF/lib/commons-validator.jar:
/WEB-INF/lib/commons-beanutils-bean-collections.jar:
/WEB-INF/lib/commons-beanutils-core.jar:
/WEB-INF/lib/commons-beanutils.jar:
/WEB-INF/lib/commons-collections.jar:
/WEB-INF/lib/commons-logging.jar:
/WEB-INF/classes/:

Take care that you have set the correct browser in the properties file.