@Secured and @PreAuthorize work fine in Controller but not working in Service level

What could be the problem ? When I use this annotation in my controller, it works fine, the page is only accessible for a ROLE_USER

@Secured("ROLE_USER") 

This annotation works also :

@PreAuthorize("hasRole('ROLE_USER')")

When I move the same annotation to my Service, it doesn't work, the method is accessible without having the ROLE_USER role !! I'm testing Spring Security, My Service is just a test (TestService interface and its implementation), whether I put the annotation in the interface or in the implementation level, as if the annotation doesn't exist.

This is my dispatcher-servlet.xml file :

<security:global-method-security secured-annotations="enabled" pre-post-annotations="enabled"/>
<bean id="TestService" class="myPackage.TestServiceImpl"/>

Thanks for helping