在spring2.5中无法使用dwr2

在spring2.5，使用schema的方式配置dwr2，spring在启动容器时，spring就会抛出如下异常:

org.springframework.beans.factory.BeanDefinitionStoreException: Unexpected exception parsing XML document from file [E:/work/.../system-service.xml]; nested exception is org.springframework.beans.FatalBeanException: Unabled to find type for beanName 'userService'. Check your bean has a correctly configured parent or provide a class for  the bean definition
 at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:405)
 at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:327)
 at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:295)
 at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:143)
 at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:178)
 at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:149)
 at org.springframework.web.context.support.XmlWebApplicationContext.loadBeanDefinitions(XmlWebApplicationContext.java:124)
 at org.springframework.web.context.support.XmlWebApplicationContext.loadBeanDefinitions(XmlWebApplicationContext.java:92)
 at org.springframework.context.support.AbstractRefreshableApplicationContext.refreshBeanFactory(AbstractRefreshableApplicationContext.java:97)
 at org.springframework.context.support.AbstractApplicationContext.obtainFreshBeanFactory(AbstractApplicationContext.java:411)
 at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:338)
 at org.springframework.web.context.ContextLoader.createWebApplicationContext(ContextLoader.java:261)
 at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:199)
 at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:45)
 at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:3763)
 at org.apache.catalina.core.StandardContext.start(StandardContext.java:4211)
 at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:759)
 at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:739)
 at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:524)
 at org.apache.catalina.startup.HostConfig.deployDescriptor(HostConfig.java:608)
 at org.apache.catalina.startup.HostConfig.deployDescriptors(HostConfig.java:535)
 at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:470)
 at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1122)
 at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:310)
 at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:119)
 at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1021)
 at org.apache.catalina.core.StandardHost.start(StandardHost.java:718)
 at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1013)
 at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:442)
 at org.apache.catalina.core.StandardService.start(StandardService.java:450)
 at org.apache.catalina.core.StandardServer.start(StandardServer.java:709)
 at org.apache.catalina.startup.Catalina.start(Catalina.java:551)
 at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
 at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
 at java.lang.reflect.Method.invoke(Method.java:597)
 at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:294)
 at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:432)
Caused by: org.springframework.beans.FatalBeanException: Unabled to find type for beanName 'userService'. Check your bean has a correctly configured parent or provide a class for  the bean definition
 at org.directwebremoting.spring.DwrNamespaceHandler$RemoteBeanDefinitionDecorator.decorate(DwrNamespaceHandler.java:334)
 at org.springframework.beans.factory.xml.NamespaceHandlerSupport.decorate(NamespaceHandlerSupport.java:106)
 at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.decorateIfRequired(BeanDefinitionParserDelegate.java:1275)
 at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.decorateBeanDefinitionIfRequired(BeanDefinitionParserDelegate.java:1264)
 at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.processBeanDefinition(DefaultBeanDefinitionDocumentReader.java:241)
 at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.parseDefaultElement(DefaultBeanDefinitionDocumentReader.java:153)
 at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.parseBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:132)
 at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.registerBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:92)
 at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.registerBeanDefinitions(XmlBeanDefinitionReader.java:488)
 at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:383)

我使用的软件版本,spring:2.5.1;dwr:2.0.3