VelocityViewServlet : Error processing a template for path '/index.vm'

Invocation of method 'get' in class mcn.idi.bieses.tools.MessagesTool threw exception java.lang.NullPointerException @ /_modules/head.vm[4,29]
java.lang.NullPointerException
	at java.util.ResourceBundle.getBundleImpl(Unknown Source)
	at java.util.ResourceBundle.getBundle(Unknown Source)
	at mcn.idi.bieses.tools.MessagesTool.getResourceValues(MessagesTool.java:128)
	at mcn.idi.bieses.tools.MessagesTool.get(MessagesTool.java:51)
	at sun.reflect.GeneratedMethodAccessor32.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
	at java.lang.reflect.Method.invoke(Unknown Source)
	at org.apache.velocity.util.introspection.UberspectImpl$VelMethodImpl.invoke(UberspectImpl.java:295)
	at org.apache.velocity.runtime.parser.node.ASTMethod.execute(ASTMethod.java:245)
	at org.apache.velocity.runtime.parser.node.ASTReference.execute(ASTReference.java:203)
	at org.apache.velocity.runtime.parser.node.ASTReference.render(ASTReference.java:294)
	at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:318)
	at org.apache.velocity.runtime.directive.Parse.render(Parse.java:224)
	at org.apache.velocity.runtime.parser.node.ASTDirective.render(ASTDirective.java:170)
	at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:318)
	at org.apache.velocity.Template.merge(Template.java:254)
	at org.apache.velocity.tools.view.servlet.VelocityViewServlet.performMerge(VelocityViewServlet.java:762)
	at org.apache.velocity.tools.view.servlet.VelocityViewServlet.mergeTemplate(VelocityViewServlet.java:719)
	at org.apache.velocity.tools.view.servlet.VelocityViewServlet.doRequest(VelocityViewServlet.java:551)
	at org.apache.velocity.tools.view.servlet.VelocityViewServlet.doGet(VelocityViewServlet.java:507)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:635)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:728)
	at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:470)
	at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:395)
	at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:316)
	at mcn.idi.bieses.servlets.JBuscar.service(JBuscar.java:59)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:493)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81)
	at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:650)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342)
	at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:800)
	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:806)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1498)
	at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.lang.Thread.run(Unknown Source)