[wildfly-dev] EntityManager is not injected inside a Jboss module

I'm working with jboss wildfly 9. I have a provider deployed as module into the   modules  directory.Then i have a jpa project with DAO pattern writing and reading inside my database. I want to handle the DAO transaction using JTA but in order to make the DAO class visibile to myprovider i need to put the DAO JPA project inside the modules directory too.Now i m facing  the real problem: it seems i cannot use the PersistenceContext annotation to inject the entity manager into my EntityManager variable wich is always null. Why i cannot inject the a context into a jar modules? What am i wrong?