org.hibernate.exception.GenericJDBCException: Field 'id' doesn't have a default value

I have this table in some application, with a generator specified and a Generationtype.AUTO, but whenever I try to persist it, I get an error from the server saying id does not have a default value. This is running on a jboss server AS7.x and the database engine is mysql.

So far I have no conclusion as to why does it happen. Can anyone help?

@SequenceGenerator(name = "id", sequenceName = "some_set_seq", initialValue = 1, allocationSize = 1)
@Table(name = "some_set")
public class SomeSet implements Serializable {

private static final long serialVersionUID = 633453570945334348L;
private long id;
private String name;
private String description;
private List<SomeItem> items;
private List<SomeEntity> someEntities;
private Date lastModification;

public SomeSet() {}

  @Id
  @GeneratedValue(strategy = GenerationType.AUTO, generator = "id")
  public long getId() {
    return id;
  }

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

  @Column(name = "name")
  public String getName() {
    return name;
  }

  public void setName(String name) {
    this.name = name;
  }

  @Column(name = "description")
  public String getDescription() {
    return description;
  }

  public void setDescription(String description) {
    this.description = description;
  }

  @OneToMany(cascade = CascadeType.ALL)
  @LazyCollection(LazyCollectionOption.FALSE)
  @JoinColumn(name = "some_set_id")
  @ForeignKey(name="FK_someItem_someSet")
  public List<SomeItem> getItems() {
    return items;
  }

  public void setItems(List<SomeItem> items) {
    this.items = items;
  }

  @ManyToMany(mappedBy = "someSets", cascade = { CascadeType.PERSIST, CascadeType.MERGE, CascadeType.REFRESH})
  @ForeignKey(name="FK_someLink_someSet")
  public List<SomeEntity> getEntities() {
    return someEntities;
  }

  public void setEntities(List<SomeEntity> someEntities) {
    this.someEntities = someEntities;
  }

  @EntityProperty(name = "lastmodificationdate")
  @Column(name = "last_modification_date")
  public Date getLastModification() {
    return lastModification;
  }

  public void setLastModification(Date lastModification) {
    this.lastModification = lastModification;
  }
}