Stateful Service Beans in Wildfly produce WELD-000079

I have an application packaged in an EAR with the following setup:

business.jar : supplies services, like data access (update, read,...) via Hibernate

data.jar : just the Entity Beans

web.war : frontend with controllers for pages

The Application is deployed on Wildfly 8.2.

The Frontend-Controllers are @ViewScoped and @Named Beans, I @Inject the services they need.

All my services are @Stateless Beans, which leads to the bottleneck of having most Hibernate Collections loaded eager.

I wanted to changed them to @Stateful to be able use a long running persistence context, but this leads to WELD-000079: Could not find the EJB in JNDI.

What did I got wrong with this concept?