Injection of @PersistenceContext does not work with abstract/base classes

I am using an "AbstractGenericDao" class for all of my DAOs.
In there I use @PersistenceContext(unitName = "myUnit") to inject the EntityManager

The concrete DAO (e.g. EmployeeDao (which extends AbstractGenericDao)) is inject (via @Inject) to a Service IMPL.

Now, when executing some logic on that DAO, where it delegates to the EntityManager (e.g. em.persist(...) I am getting a NullPointerException, indicating that the EntityManager is NULL