JAXB problems

Hello? keep an eye on the fllowing code:

public void GetCard (String Id) {
try {
Core c = new Core();
Connection con= c.getConnection();
JAXBContext jc = JAXBContext.newInstance( "it.mais.micromais.MACA" );
ObjectFactory of = new ObjectFactory();
//MACA
MACA maca = of.createMACA();
String IdMACA = Id;
int MACAsize = 2;
String MACA = "MA_CA";
Vector MACAValuesList = c.LoadTableValuesList(Id, MACA, con, MACAsize);
if (MACAValuesList!=null){
maca.setIdMACA((String)MACAValuesList.elementAt(0));
maca.setMACA((String)MACAValuesList.elementAt(1));
}
MACAType.DAType da = of.createMACATypeDAType();
int DAsize = 1;
String DA = "DA";
if (MACAValuesList!=null){
Vector DAVectorValuesList = c.LoadChildValuesList(IdMACA, MACA, DA, con ,DAsize);
for (int i=0; i<DAVectorValuesList.size(); i++){
Vector DAValuesList = (Vector)DAVectorValuesList.get(i);
String IdDA = (String)DAValuesList.elementAt(0);
da.setIdDA((String)DAValuesList.elementAt(0));
}
}
Marshaller m = jc.createMarshaller();
m.setProperty( Marshaller.JAXB_FORMATTED_OUTPUT, Boolean.TRUE );
m.marshal( maca, System.out );
} catch( JAXBException je ) {
je.printStackTrace();
}
}

The program get variables from a Sybase Server. The result should it be like this

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<MA_CA IdMA_CA="1" MA_CA="Scheda"/>
<DA IdDA="1"/>
<DA IdDA="2"/>
<DA IdDA="3"/>

But I obtain:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<MA_CA IdMA_CA="1" MA_CA="Scheda"/>,

no trace of Da.
.