[Spring] Problema con controller annotation

[fermat]

ciao!

sto cercando di usare i controller con le annotations.
questo il controller:

@Controller
@RequestMapping("/")
public class IndexController {

    @RequestMapping(method = RequestMethod.GET)
    public ModelAndView helloWorld(HttpServletRequest request, HttpServletResponse response) throws Exception {
        ModelAndView model = new ModelAndView("index");
        model.addObject("msg", "hello world");
        return model;
    }

}

questo il dispatcher-servlet.xml

<?xml version='1.0' encoding='UTF-8' ?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:p="http://www.springframework.org/schema/p"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xmlns:tx="http://www.springframework.org/schema/tx"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
       http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.0.xsd
       http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.xsd">
    
    <bean id="viewResolver"
          class="org.springframework.web.servlet.view.InternalResourceViewResolver" >
        <property name="prefix">
            <value>/WEB-INF/jsp/</value>
        </property>
        <property name="suffix">
            <value>.jsp</value>
        </property>
    </bean>

</beans>

e infine l'applicationContext.xml:

<?xml version='1.0' encoding='UTF-8' ?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:p="http://www.springframework.org/schema/p"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xmlns:tx="http://www.springframework.org/schema/tx"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
       http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.0.xsd
       http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.xsd">
    
    <context:component-scan base-package="com.mp" />

</beans>

nel web.xml ho messo così:

<listener>
        <!--<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>-->
        <listener-class>org.springframework.web.context.request.RequestContextListener</listener-class>
    </listener>

ma ottengo sempre un HTTP Status 400.
da cosa può dipendere??