Spring's @Scheduled error : Only one AsyncAnnotationBeanPostProcessor may exist within the context

I am trying Spring 3's @Scheduled annotation . Here is my configuration (app.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:context="http://www.springframework.org/schema/context"
  xmlns:aop="http://www.springframework.org/schema/aop"
  xmlns:tx="http://www.springframework.org/schema/tx"
  xmlns:task="http://www.springframework.org/schema/task"
  xsi:schemaLocation="
      http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
      http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd
      http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.0.xsd
      http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.0.xsd
      http://www.springframework.org/schema/task http://www.springframework.org/schema/task/spring-task-3.0.xsd
      "
>

  <context:component-scan base-package="destiny.web"/>  
  <context:annotation-config/>
  // other beans

  <task:annotation-driven executor="myExecutor" scheduler="myScheduler"/>
  <task:executor  id="myExecutor"  pool-size="5"/>
  <task:scheduler id="myScheduler" pool-size="10"/>
</beans>

And this is my service class :

@Service
public class ServiceImpl implements Service , Serializable
{
  //other injections

  @Override
  @Transactional
  public void timeConsumingJob()
  {
    try
    {
      Thread.sleep(10*1000);
    }
    catch (InterruptedException e)
    {
      e.printStackTrace();
    }
  }

  @Override
  @Scheduled(cron="* * * * * ?") 
  public void secondly()
  {
    System.err.println("secondly : it is " + new Date());
  }
}

It works fine when testing in my eclispe + junit , when testing a time