Spring transaction propagation problem

In our Java project, we use ORM with hibernate and spring. I had problems deleting persistent objects. For example, this sample method retrieves objects using identifiers and then deletes them:

@Transactional
public void remove(List<Long> ids) {
    SearchTemplate template = new SearchTemplate();
    template.addParameter("milestoneId",ids);
    List <InvoiceQueue> items = this.findByCriteria(template);
    ...
    this.delete(items);
}

The method executes Ok without any exceptions, but does not actually delete items from the database.

Adding the following annotation to the method definition @Transactional(propagation = Propagation.REQUIRES_NEW)solves the problem.

Can someone explain why it does not work with the default distribution type PROPAGATION_REQUIRED.

Thanks in advance.

Environmental Information:

hibernate.version 3.5.5-Final, spring.version 3.0.5.RELEASE