✔ JPA Toplink Derby "Drop and Create Tables" funktioniert nicht!

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="1.0" xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd">
  <persistence-unit name="KeyGenPU" transaction-type="JTA">
    <provider>oracle.toplink.essentials.PersistenceProvider</provider>
    <jta-data-source>jdbc/sample</jta-data-source>
    <properties>
      <property name="toplink.ddl-generation" value="drop-and-create-tables"/>
    </properties>
  </persistence-unit>
</persistence>

@Entity
@Table(name = "NEWENTITY")
@NamedQueries({@NamedQuery(name = "Newentity.findById", query = "SELECT n FROM Newentity n WHERE n.id = :id"), @NamedQuery(name = "Newentity.findByFirstname", query = "SELECT n FROM Newentity n WHERE n.firstname = :firstname")})
public class Newentity implements Serializable {
    private static final long serialVersionUID = 1L;
    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    @Column(name = "ID", nullable = false)
    private Long id;
    @Column(name = "FIRSTNAME")
    private String firstname;

    public Newentity() {
    }

    public Newentity(Long id) {
        this.id = id;
    }

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getFirstname() {
        return firstname;
    }

    public void setFirstname(String firstname) {
        this.firstname = firstname;
    }
}