Mapeamento bi-direcional (Hibernate)

Estou tentando realizar um mapeamento bi-direcional entre a classe Motorist e a classe Vehicle, mas está gerando erro. Alguém pode me ajudar?
Agradeço a atenção.

motorist.hbm.xml:

<set name="vehicles" inverse="true"> <key column="MOT_ID"/> <one-to-many class="Vehicle"/> </set>

vehicle.hbm.xml:

Exceção gerada:

Dec 19, 2010 9:41:27 PM org.springframework.beans.factory.support.DefaultSingletonBeanRegistry destroySingletons
INFO: Destroying singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@bb7465: defining beans [dataSource,sessionFactory,transactionManager,rantDao]; root of factory hierarchy
Exception in thread “main” org.springframework.beans.factory.BeanCreationException: Error creating bean with name ‘sessionFactory’ defined in class path resource [spring.xml]: Invocation of init method failed; nested exception is org.hibernate.MappingException: Association references unmapped class: Vehicle
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1420)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:519)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456)
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:291)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:288)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:190)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:563)
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:895)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:425)
at org.springframework.context.support.ClassPathXmlApplicationContext.(ClassPathXmlApplicationContext.java:139)
at org.springframework.context.support.ClassPathXmlApplicationContext.(ClassPathXmlApplicationContext.java:83)
at Main.main(Main.java:8)
Caused by: org.hibernate.MappingException: Association references unmapped class: Vehicle
at org.hibernate.cfg.HbmBinder.bindCollectionSecondPass(HbmBinder.java:2380)
at org.hibernate.cfg.HbmBinder$CollectionSecondPass.secondPass(HbmBinder.java:2662)
at org.hibernate.cfg.CollectionSecondPass.doSecondPass(CollectionSecondPass.java:43)
at org.hibernate.cfg.Configuration.secondPassCompile(Configuration.java:1130)
at org.hibernate.cfg.Configuration.buildMappings(Configuration.java:1115)
at org.springframework.orm.hibernate3.LocalSessionFactoryBean.buildSessionFactory(LocalSessionFactoryBean.java:717)
at org.springframework.orm.hibernate3.AbstractSessionFactoryBean.afterPropertiesSet(AbstractSessionFactoryBean.java:211)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1477)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1417)
… 12 more

Só para constar, estou usando Spring junto com Hibernate, e ambos as classes (Motorist e Vehicle) estão referenciadas no arquivo de configuração do Hibernate e no contexto de aplicação no mappingResources do Spring.

ninguém? =S