spring注入的问题

<bean id="transactionManager" class="org.springframework.orm.hibernate3.HibernateTransactionManager">
        <property name="sessionFactory" ref="sessionFactory"/>
    </bean>
    <bean id="transactionInterceptor" class="org.springframework.transaction.interceptor.TransactionInterceptor">
        <property name="transactionManager" ref="transactionManager"/>
     <property name="transactionAttributes">
    <props>
    <prop key="get*">PROPAGATION_REQUIRED,readOnly</prop>
     <prop key="*">PROPAGATION_REQUIRED</prop>
    </props>
    </property>
</bean>    <!-- 定义BeanNameAutoProxyCreator-->
    <bean class="org.springframework.aop.framework.autoproxy.BeanNameAutoProxyCreator">
    <property name="beanNames">
            <list>
                   <value>mappingService</value>
                   <value>productService</value>
                   <value>testHibernate</value>
            </list>
    </property>
        <property name="interceptorNames">
            <list>
                <value>transactionInterceptor</value> 
            </list>
        </property>
    </bean><bean id="testHibernate" class="com.service.impl.TestHibernate">
     <property name="areadao">
            <ref bean="areadao"/>
        </property>
    </bean>java类
[code]
import com.dao.AreaCodeDAO;public class TestHibernate {
private AreaCodeDAO areadao; public void setAreadao(AreaCodeDAO areadao) {
System.out.println("==========开始注入areadao=========");
this.areadao = areadao;
System.out.println("areadao:"+areadao);
}

public void test(){
System.out.println("run--------areadao:"+areadao);
areadao.getCount("uncompleted");
}
}[/code]
服务器启动：
==========开始注入areadao=========
areadao:com.dao.AreaCodeDAO@1f1f38e
外部调用：
run--------areadao:null为什么变成了NULL了呢，大侠们帮忙看看，谢谢啊！