Giulio, Thanks for your response. I have tried "Persistence.createEntityManagerFactory( "PersistenceUnitName"), null);" in a main class in the same project that I am trying to test Jaser reports. It works in the following way: If the Persistence Unit exist in the project: If I have the libraries of TopLink in the project, it works. I have tried with both toplink-essentials-agent.jar and toplink-essentials.jar, and with each one separately, and it works in all the ways. If I do not have such libraries in the project, the message of the exception is "No Persistence provider for EntityManager named ..." If the Persistence Unit does not exist in the project, the message of the exception is always "No Persistence provider for EntityManager named ...".So, I am guessing that the classpath of my project, is well configured, and the problem is and issue with the iReports plugin. Anyway, I have tried add the TopLink libraries to iReport classpath (Tools - Options - iReport - Classpath), with the following results at the moment of creating a new EJBQL connection with the wizard: If the library added is toplink-essentials.jar, the message exception is always "oracle.toplink.essentials.PersistenceProvider cannot be cast to javax.persistence.spi.PersistenceProvider", whatever the Persistent Unit exists or not. If the library added is toplink-essentials-agent.jar (instead of toplink-essentials.jar), the message exception is always "No Persistence provider for EntityManager named ...", whatever the Persistent Unit exists or not. I have also tried adding the jar of the project, and the source folder of the project (where "META-INF/persistence.xml" resides) in the classpath of iReport, and the results are the same as above.I really don't know what to try next. I would appreciate any tip on that. Thanks very much, tizo