I have a User Registration Form for entering user details. In this form there is one field for setting User Group,
I am able to populate the values into the combo box(from the database) but when i submit the form ,an exception occurs and i didn't get the combobox selected user group value .

Exception:
INFO [lifecycle] WARNING: FacesMessage(s) have been enqueued, bu
may not have been displayed.
sourceId = j_id10:j_id46[severity=(ERROR 2), summary=(value is required), detail
value is required)]


Please help me to solve this problem....

Combo box xhtml code:

<h:outputLabel>Group:</h:outputLabel></td>
       
<h:selectOneMenu name="group" id="userGroupId" value="#{userBean.userGroupId}" tabindex="4" >

<s:selectItems value="#{groups}" var="group"  label="#{group.groupReferenceId}" itemValue="#{group}" noSelectionLabel="-- Select Group --" />
                                                                        <s:convertEntity/>
</h:selectOneMenu>
                                                                                               
Action Class:-

@Stateful
@Name("userAction")
@Scope(SESSION)
public class UserAction implements User, Serializable{
       
        private GroupBean groupBean = null;
       
        @PersistenceContext 
        private EntityManager em = null;
       
        @Logger
        private static Log log = null;
       
        @DataModel  
        private List<GroupBean> groups = null;
       
       
        @In
        private transient FacesContext facesContext;

       
       
        public String addUser() {
               
                userBo = new UserBO();
                groups = em.createQuery("select group from
                         GroupBean group").getResultList();
                return "addUser";
               
        }
       

               
        @Destroy @Remove
        public void destroy() {
                
                
        }

}                                                                                              
                                                                        Entity Bean:--

@Entity
@Name("groupBean")
@Scope(SESSION)
public class GroupBean implements Serializable{
       
        private static final long serialVersionUID = 1L;
        private String groupId = null;
    private String groupReferenceId = null;

        public GroupBean() {
               
        }
        public GroupBean(String groupId, String groupReferenceId){
                this.groupId = groupId;
                this.groupReferenceId = groupReferenceId;
        }
       
        @Id @GeneratedValue
        public String getGroupId() {
                return groupId;
        }
        
        public void setGroupId(String groupId) {
                this.groupId = groupId;
        }
       
        public String getGroupReferenceId() {
                return groupReferenceId;
        }
       
        public void setGroupReferenceId(String groupReferenceId) {
                this.groupReferenceId = groupReferenceId;
        }

}