CMP entity bean - javax.ejb.CreateException: Primay key for created instance is null

Hi,
I'm trying to develope a CMP entity bean under jboss with mysql db.
My entity bean must have an autoincrement primary key.

The following is part of my: standardjbosscmp-jdbc.xml

 <unknown-pk>
  <key-generator-factory>UUIDKeyGeneratorFactory</key-generator-
factory>
  <unknown-pk-class>java.lang.Object</unknown-pk-class>
  <field-name>id</field-name>
  <column-name>id</column-name>
  <jdbc-type>INTEGER</jdbc-type>
  <sql-type>INT(11)</sql-type>
  <auto-increment/>
 </unknown-pk>
 <entity-command name="default"/>

  I have deployed my entity bean without problems and the following
 is my deployment descriptor:


<ejb-jar>
<enterprise-beans>
<entity>
        <ejb-name>fisrtEJB</ejb-name>
        <home>my.java.test.FirstHomeRemote</home>
	<remote>my.java.test.FirstRemote</remote>
	<ejb-class>my.java.test.FirstBean</ejb-class>
	<persistence-type>Container</persistence-type>
	<prim-key-class>java.lang.Object</prim-key-class>
	<reentrant>False</reentrant>
	<abstract-schema-name>MySchema</abstract-schema-name>
	<cmp-field><field-name>name</field-name></cmp-field>
	<cmp-field><field-name>surname</field-name></cmp-field>
	<cmp-field><field-name>mobile</field-name></cmp-field>
	<security-identity><use-caller-identity/></security-identity>
</entity>
</enterprise-beans>
<assembly-descriptor>
....
etc

NB: I don't specify cmp id field! It is correct?

When I have deployed entity bean the created table have
id,name,surname and mobile fields

interface:

public interface FirstHomeRemote extends javax.ejb.EJBHome{
 public FirstRemote create() throws CreateException, RemoteException;
 public FirstRemote findByPrimaryKey(Object pk) throws
FinderException, RemoteException;
}

FirstBean:

 public Object ejbCreate()throws CreateException{
   return null;
 }

 public void ejbPostCreate(){
  }

In this class I don't have implemented cmp field id.

The FirstRemote class contains abstract method: setName(),getName()
etc...


Now let's see the client:


   Context jndiContext = getInitialContext(); // get jnp://localhost:
1099 etc..
   Object ref = jndiContext.lookup("FirstEJB");
   FirstHomeRemote home = (FirstHomeRemote)
    ****tableRemoteObject.narrow(ref,FirstHomeRemote.class);

    FirstRemote myfirst = (FirstRemote)home.create();
    myfirst.setName("John");


   the statement:  FirstRemote myfirst = (FirstRemote)home.create();

    return exception: javax.ejb.CreateException: Primary key for
created instance is null.

    Within created table I see that id (autoincrement primary key)
    is added  and Jboss server.log don't return errors, so I can't
figure
    It out this problems..



please help me.
Teo