when set a value to combobox the hidden field don't received the value.. I need select the item in combobox to my hidden field receveid the value.. the problem:

my form have a combobox that have the country that the person live.. when the user go update your profile.. I need reset this field and do the user to select you country again...

Code:
		ListStore<TestModel> store = new ListStore<TestModel>();

		TestModel model = new TestModel();
		model.setCodigo(1);
		model.setNome("name 1");

		TestModel model1 = new TestModel();
		model1.setCodigo(2);
		model1.setNome("name 2");

		store.add(model);
		store.add(model1);

		FormPanel form = new FormPanel();

		ComboBox<TestModel> combo = new ComboBox<TestModel>();
		combo.setStore(store);
		combo.setFieldLabel("xxx");
		combo.setDisplayField("nome");
		combo.setValueField("codigo");
		combo.setName("comboBox");
		combo.setValue(model);

		form.add(combo);

		RootPanel.get().add(form);
TestModel.java
Code:
public class TestModel extends BaseModel {

	public Integer getCodigo() {
		return get("codigo");
	}

	public String getNome() {
		return get("nome");
	}

	public void setCodigo(Integer codigo) {
		set("codigo", codigo);
	}

	public void setNome(String nome) {
		set("nome", nome);
	}

}