Thanks for your reply. I found out the the database connection is ok and it is working as defined.
My fault was that I defined in my pesistence.xml the jta-data-source with
but the prafix "java:/" is necessary for jboss (?). After I changed the jta-data-source tag to:
the application works well and all tables in my database were generated correctly.
This is confusing because on a Glassfish Server the jta-data-source is always declared without the prafix "java:/" . So it seems to me that the persistence.xml configuration is depending on the app-server platform :-/
By default Datasource in JBoss is declared with the prefix "java:/", but you can set use-java-context to false in xx-ds.xml to remove the "java:/" prefix.
Thanks a lot - yes this works !