The name of the driver class for the datasource is missing (Netbeans+ PostgreSql + Glassfish)

Question

I'm trying to develop an EJB application using Netbeans 8 on a Postgres 9.2 db and Glassfish 4 server.

Once I created connection pool and JDBC resources in the glassfish admin panel, I'm not able to add entities using the datasource. Netbeans still giving me an error:

The name of the driver class for the datasource is missing

I've already tried adding libraries to the project. I copied postgresql-9.2-1002.jdbc4.jar and postgresql-9.2-1002.jdbc3.jar files in C:\Program Files\glassfish-4.0\glassfish\domains\domain1\lib folder.

Screenshot: http://imageshack.com/a/img843/6884/w3ko.png

If I create entities using a connection created before(in NB Services/Databases), it works, but result set after any query is empty. Any idea?

Here the connection pool I created: http://imageshack.com/a/img838/8286/bkw8.png

This is my persistence.xml:

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.1" xmlns="http://xmlns.jcp.org/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd">
  <persistence-unit name="Esempio-ejbPU" transaction-type="JTA">
    <jta-data-source>try_</jta-data-source>
    <exclude-unlisted-classes>false</exclude-unlisted-classes>
    <properties>
      <property name="javax.persistence.schema-generation.database.action" value="create"/>
    </properties>
  </persistence-unit>
</persistence>

Answer 1

Solved: it was a connection pool issue. Creating a driver one in glassfish admin panel I've got no more problems.