JSF-2 - f:ajax-tag funktioniert nicht

Ich habe ein problem mit f:ajax-tag. In meinem vorherigen Projekt, funktionierte alles perfekt. Jetzt habe ich ein anderes Projekt und f:ajax-tag funktioniert überhaupt nicht und ich weiß nicht, warum.

Habe ich dies in JSF-Seite mit Facelets:

<h:form>
...
    <h:selectOneMenu id="employeeId" value="#{employeeBean.employeeId}">
        <f:selectItems value="#{employeeBean.employeesSelectItem}"/>
        <f:ajax event="change" listener="#{employeeBean.changeOwner}"/>
     </h:selectOneMenu>
...
</h:form>

Und employeeBean mit changeOwner-Methode mit Datenbank-Zugriff:

...
public void changeOwner(AjaxBehaviorEvent event) {
    try {
        update.updateOwner(...params...);
        JSF.setMessage(Messages.UPDATE_OK);
    } catch (UpdateDBException ex) {
        JSF.setMessage(ex.getMessage());
    }
}
...

Kann ich nicht sehen, nichts falsch. Danke für die Hilfe.

UPDATE

faces-config:

<faces-config version="2.0"
    xmlns="http://java.sun.com/xml/ns/javaee" 
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-facesconfig_2_0.xsd">

    <converter>
        <converter-for-class>java.util.Date</converter-for-class>
        <converter-class>misc.TimeZoneConverter</converter-class>
    </converter>
</faces-config>

xhtml-Seite:

<ui:composition xmlns:ui="http://java.sun.com/jsf/facelets"
            template="./../templates/mainTemplate.xhtml"
            xmlns:h="http://java.sun.com/jsf/html"
            xmlns:f="http://java.sun.com/jsf/core">

<ui:define name="content">
    <h2>Smazání zaměstnance</h2>
            Protože s daným zaměstnancem (#{employeeBean.employee.name} #{employeeBean.employee.surname}) souvisejí některé úkoly, je potřeba, aby se jich ujal jiný. Vyberte prosím nové zaměstnance u všech níže uvedených úkolů.
            <h:form>
                <h:dataTable value="#{taskBean.employeeTasks}" var="item">
                    <h:column>
                        <f:facet name="header">ID</f:facet>
                        <center>#{item.idtask}</center>
                    </h:column>
                    <h:column>
                        <f:facet name="header">Zadavatel</f:facet>
                        <h:selectOneMenu id="managerId" value="#{employeeBean.newManagerId}" rendered="#{employeeBean.employeeId == item.employeeByIdmanager.idemployee}">
                            <f:selectItems value="#{employeeBean.otherEmployeesSelectItem}"/>
                            <f:ajax event="change" listener="#{employeeBean.changeOwner}"/>
                        </h:selectOneMenu>
                        <h:outputText value="#{item.employeeByIdmanager.name} #{item.employeeByIdmanager.surname}" rendered="#{employeeBean.employeeId != item.employeeByIdmanager.idemployee}"/>
                    </h:column>
                    <h:column>
                        <f:facet name="header">Zodpovědná osoba</f:facet>
                        <h:selectOneMenu id="employeeId" value="#{employeeBean.newEmployeeId}" rendered="#{employeeBean.employeeId == item.employeeByIdemployee.idemployee}">
                            <f:selectItems value="#{employeeBean.otherEmployeesSelectItem}"/>
                            <f:ajax event="change" listener="#{employeeBean.changeOwner}"/>
                        </h:selectOneMenu>
                        <h:outputText value="#{item.employeeByIdemployee.name} #{item.employeeByIdemployee.surname}" rendered="#{employeeBean.employeeId != item.employeeByIdemployee.idemployee}"/>
                    </h:column>
                    <h:column>
                        <f:facet name="header">Čas zadání</f:facet>
                        <center><h:outputText value="#{item.timestart}"/></center>
                    </h:column>
                    <h:column>
                        <f:facet name="header">Udělat do</f:facet>
                        <center><h:outputText value="#{item.timetodo}"/></center>
                    </h:column>
                    <h:column>
                        <f:facet name="header">Popis úkolu</f:facet>
                        #{item.text}
                    </h:column>
                    <h:column>
                        <f:facet name="header">Zákazník</f:facet>
                        <h:link outcome="viewCustomerDetails">
                            <h:panelGrid columns="1">
                                <h:outputText value="#{item.customer.name}"/>
                                <h:outputText value="#{item.customer.addresscity}"/>
                            </h:panelGrid>
                            <f:param name="customerId" value="#{item.customer.idcustomer}"/>
                        </h:link>
                    </h:column>
                    <h:column>
                        <f:facet name="header">Stav úkolu</f:facet>
                        #{item.taskstate.state}
                    </h:column>
                    <h:column>
                        <f:facet name="header">Poznámky</f:facet>
                        <h:outputText escape="false" value="#{item.note}"/>
                    </h:column>
                </h:dataTable>
            </h:form>

    <h:messages globalOnly="true" styleClass="messages"/>
</ui:define>

UPDATE2

EmployeeBean:

package beans;
import beans.jsf.JSF;
import ejb.Get;
import ejb.Update;
import entities.Employee;
import entities.Permission;
import java.util.ArrayList;
import java.util.List;
import javax.ejb.EJB;
import javax.faces.bean.ManagedBean;
import javax.faces.bean.ManagedProperty;
import javax.faces.bean.RequestScoped;
import javax.faces.model.SelectItem;
import javax.validation.constraints.Pattern;
import misc.Messages;

@ManagedBean(name="employeeBean")
@RequestScoped
public class EmployeeBean {

@EJB
private Get get;

@EJB
private Update update;

@ManagedProperty(name="employeeId", value="#{param['employeeId']}")
private int employeeId;

private int newManagerId;

private int newEmployeeId;

private String edit = "none";

@Pattern(regexp=".+", message="Jméno musí být vyplněno.")
private String name;

@Pattern(regexp=".+", message="Příjmení musí být vyplněno.")
private String surname;

private int permissionId;

private Employee employee;

/** Creates a new instance of EmployeeBean */
public EmployeeBean() {
}

public int getNewEmployeeId() {
    return newEmployeeId;
}

public void setNewEmployeeId(int newEmployeeId) {
    this.newEmployeeId = newEmployeeId;
}

public int getNewManagerId() {
    return newManagerId;
}

public void setNewManagerId(int newManagerId) {
    this.newManagerId = newManagerId;
}

public int getEmployeeId() {
    return employeeId;
}

public void setEmployeeId(int employeeId) {
    this.employeeId = employeeId;
    employee = get.getEmployee(employeeId);
}

public String getEdit() {
    return edit;
}

public void setEdit(String edit) {
    this.edit = edit;
}

public String getName() {
    return name;
}

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

public int getPermissionId() {
    return permissionId;
}

public void setPermissionId(int permissionId) {
    this.permissionId = permissionId;
}

public String getSurname() {
    return surname;
}

public void setSurname(String surname) {
    this.surname = surname;
}

public Employee getEmployee() {
    return employee;
}

public void setEmployee(Employee employee) {
    this.employee = employee;
}

private void showEdit() {
    edit = "block";
}

private void hideEdit() {
    edit = "none";
}

/**
 * Naplní SelectItem všemi zaměstnanci.
 * @return seznam zaměstnanců
 */
public List<SelectItem> getEmployeesSelectItem() {
    List<SelectItem> employees = new ArrayList<SelectItem>();

    for (Employee e : get.getEmployees()) {
        employees.add(new SelectItem(e.getIdemployee(), e.getName() + " " + e.getSurname()));
    }

    return employees;
}

/**
 * Vrátí seznam zákazníků.
 * @return seznam zákazníků
 */
public List<Employee> getEmployees() {
    return get.getEmployees();
}


/**
 * Načte úkol pro editaci.
 */
public void loadEmployee() {
    Employee e = get.getEmployee(employeeId);

    if (e != null) {
        name = e.getName();
        surname = e.getSurname();
        permissionId = e.getPermission().getIdpermission();

        showEdit();
    } else {
        JSF.setMessage(Messages.DB_RETURN_NULL);
    }
}

/**
 * Naplní SelectItem všemi oprávněními.
 * @return seznam oprávnění
 */
public List<SelectItem> getPermissionsSelectItem() {
    List<SelectItem> permissions = new ArrayList<SelectItem>();

    for (Permission p : get.getPermissions()) {
        permissions.add(new SelectItem(p.getIdpermission(), p.getPermissionname()));
    }

    return permissions;
}    

/**
 * Zapíše úpravy úkolu.
 */
public void updateEmployee() {
    try {
        update.updateEmployee(name, surname, employeeId, permissionId);
        JSF.setMessage(Messages.EMPLOYEE_UPDATE_OK);
    } catch (Exception ex) {
        showEdit();
        JSF.setMessage(ex.getMessage());
    } 
}

/**
 * Zruší prováděné úpravy a skryje editaci.
 */
public void cancel() {
    hideEdit();
}

public void changeOwner(int taskId) {
    System.out.println("taskId: "+taskId);
    System.out.println("managerId: "+newManagerId);
    System.out.println("employeeId: "+newEmployeeId);
//       try {
//           update.updateOwner(taskId, newManagerId, newEmployeeId);
//           JSF.setMessage(Messages.UPDATE_OK);
//       } catch (UpdateDBException ex) {
//           JSF.setMessage(ex.getMessage());
//       }
}

/**
 * Naplní SelectItem všemi možnými stavy pro úkol.
 * @return seznam stavů úkolu
 */
public List<SelectItem> getOtherEmployeesSelectItem() {
    List<SelectItem> employees = new ArrayList<SelectItem>();

    for (Employee e : get.getOtherEmployees(employeeId)) {
        employees.add(new SelectItem(e.getIdemployee(), e.getName() + " " + e.getSurname()));
    }

    return employees;
}
}