JSF2 - h:commandButton not working with multiple SelectOneMenus

Question

I'm quite new to JEE6 & JSF in specific, so I know I'm lacking some knowledge to get this running. I was trying to get in work for over two days know - it's desperating...

What is my problem: I have a user, skills and level, e.g. "Frank (The Cook)" has skill "Cooking" with level "expert". Therefore I try to create a form where a user can manage his skills. I can manage to display a skill with according level. The level is a selected value of a SelectOneMenu. When I change the value and submit the form it simply does nothing and I don't know why :-(

My code so far:

profile.xhtml

<h5>General skills</h5>
<h:panelGroup>
    <h:form>
        <h:dataTable value="#{userBean.userskills}" var="userskill">
            <h:column>
                <f:facet name="header">Skill</f:facet>
                <span><h:outputText value="#{userskill.skill.description}" /></span>
            </h:column>

            <h:column>
                <f:facet name="header">Level</f:facet>
                <span>
                    <h:selectOneMenu value="#{userskill.level}" >
                        <f:selectItem itemValue="#{null}"
                                      itemLabel="#{msg.ChooseOption}"
                                      noSelectionOption="true" />
                        <f:selectItems value="#{userskill.skill.levels}"
                                       var="level"
                                       itemValue="#{level}"
                                       itemLabel="#{level.description}" />
                        <f:converter converterId="levelConverter" />
                    </h:selectOneMenu>
                </span>
            </h:column>
        </h:dataTable>
        <h:commandButton value="#{msg.Save}" 
                         action="#{userBean.testAction}" />
    </h:form>
</h:panelGroup>

UserBean.java

@ManagedBean
@SessionScoped
public class UserBean implements Serializable {
    private static final long serialVersionUID = 1L;

    private User user;

    @ManagedProperty(value="#{authBean}")

    private AuthenticationBean authBean;

    @EJB IUserDao userDao;
    @EJB ICategoryDao categoryDao;
    @EJB IUserSkillLevelDao uskDao;

    List< UserSkillLevel > userskills;

    public User getUser() {
         return user;
    }

    public void setUser(User user) {
         this.user = user;
    }

    public void setAuthBean(AuthenticationBean authBean) {
         this.authBean = authBean;
    }

    public List<UserSkillLevel> getUserskills() {
         return userskills;
    }

    public void setUserskills(List<UserSkillLevel> userskills) {
         this.userskills = userskills;
    }

    public String getProfile(Long userId) {
         // is called when clicking on the "Show user profile" link on an other page
         User auth_user = this.authBean.getUser();
         if ( auth_user.getId() == userId ) {
             this.user = auth_user;
         } else {
             this.user = userDao.findById(userId);
         }

         this.userskills = findUserskills(null, false);

         return "/pages/profile?faces-redirect=true";
    }

    public List< UserSkillLevel > findUserskills(Category category, boolean skillIsWithStandardLevelSet) {
         if ( category == null ) {
             Map<String, Object> parameters = new HashMap<String, Object>();
             parameters.put("description", "General");
             category = categoryDao.findOneByConditions(Category.FIND_BY_DESCRIPTION, parameters);
         }
         return uskDao.findByUserAndCategory(this.user, category, skillIsWithStandardLevelSet);
    }

    public String testAction() {
        System.out.println("-------- worked --------");
        return "";
    }
}

It all works fine. The level (from DB) is displayed on startup, the converter is converting vise-versa and the SelectOneMenu contains the level specified for that skill.

I think the commandButton is not working because of the automatically generated SelectOneMenus. Am I right? When debugging my code I found out that userBean.userskills.level changed from initial value to null but I couldn't figure out if it contains the selected value after changing it. As soon as I remove the SelectOneMenu the commandButton calls testAction as intended.

What am I doing wrong? I'm missing something but I don't know what :-( Is there an easier way to accomplish what I want? In addition: I have to stick with plain JSF, that means no use of Primefaces, Omnifaces, etc.

Greetings, Stefi

-- UPDATE --

I added a h:message to my SelectOneMenu and encountered a "Value not valid"-Error; trying to figure out why it appears...

-- UPDATE --

IT'S WORKING ;-) Just for those who are desperated like I was: I just forgot to implement a equals method for my entity!!!