jsp error message not displaying

on JSP when I want to display error messages but when开发者_如何学Go it returns to JSP page by

<form:errors path="arnNumber" cssClass="error" /></span>

it is giving me an exception

org.springframework.context.NoSuchMessageException: No message found under code 'ARN number is required.contactUsUtil.arnNumber' for locale 'en_US'.

Literally translated, it just means that it cannot find any message associated with the following key

ARN number is required.contactUsUtil.arnNumber

The key looks suspicious :)

define it under Application context

<bean id="responseMessageSource"
class="org.springframework.context.support.ReloadableResourceBundleMessageSource">
    <property name="cacheSeconds" value="3"/>
    <property name="basename" value="classpath:response_msg" />
    <property name="defaultEncoding" value="UTF-8"/>
</bean>

define under resource folder ,it is easy

NO_SESSION=SESSION ERROR
NO_PHOTO=The photo with specified id couldn't find
SUCCESSFULL_CRATED_ALBUM=Album has created successfully
ASSIGNED_ALBUM_PHOTO=This photo assigned as your album photo.
SUCCESFULL_UPDATED_ALBUM=Album has updated successfully
SUCCESFULL_UPDATED_PHOTO=Photo has updated successfully
SUCCESFULL_CRATED_IMAGE_DIRECTORY=Image directories created successfully