Struts Form Problem

[Amy]

When accessing my JSP I get the following error:
org.apache.jasper.JasperException: Missing message for key
button.next

Can anyone tell me what the problem is? I have tried to figure this
out but am new to building webapps and struts. Thank you for your
help.

My JSP has :
<html:form action="/ContactAction">
<html:submit property="action">
<bean:message key="button.next"/>
</html:submit>
<html:submit property="action">
<bean:message key="button.back"/>
</html:submit>
<html:submit property="action">
<bean:message key="button.finish"/>
</html:submit>
</html:form>

My FormHandler has :

public final class ContactFormHandler extends LookupDispatchAction{
protected Map getKeyMethodMap(){
Map map = new HashMap();
map.put("button.next", "next");
map.put("button.back", "back");
map.put("button.finish", "finish");
return map;
}
public ActionForward next(ActionMapping mapping,
ActionForm form,
HttpServletRequest request,
HttpServletResponse response)
throws IOException, ServletException {
return mapping.findForward("success");
}

public ActionForward back(ActionMapping mapping,
ActionForm form,
HttpServletRequest request,
HttpServletResponse response)
throws IOException, ServletException {
return mapping.findForward("success");
}

public ActionForward finish(ActionMapping mapping,
ActionForm form,
HttpServletRequest request,
HttpServletResponse response)
throws IOException, ServletException {
return mapping.findForward("success");
}

My ApplicationResource.properties file contains only

button.next = Next
button.back = Back
button.finish = Finish