JBOSS 5 has improved ejb-3 support, and there are some subtle differences between the servers 4.X and 5.X. Edit your persistence.xml file and see if you have something like:
Furthermore you MUST define all you're classes (if you're using annotations).
Thank you for your answer.
I use JBoss 5.1.0.GA-jdk6-
The jta-data-source is defined, but Is really must define all annotated entity? :(
Hmm, no, you don't need to define your Entities in persistence.xml.
De app container will scan for annotated entities (JPA 1.5 and beyond).
'JPA 1.5 and beyond' meaning JPA for JDK 1.5 and beyond :)
anything else, I use jbpm integration with the same project, but I don't think this causes the problem.
The probleam was solved. There was an empty persistence.xml and orm.xml under the web project that generated an earlier seam-gen version.