Java HotSpot Virtual Machine

Hi,
I'm currently using hibernate spring and JSF

1/ the first problem
In the JSF common header page I try to test if a bean is in the session scope in order to show login or logout link, and the test always fails : the logout link is always displayed.

the JSF page :

<f:subview id="header" >
  
	
    <h:form id="headerForm">
        <table cellspacing="0" width="100%">
    <tr>
        <td align="left" valign="middle">
    		<a href="front.jsf"><img border="0" src="images/logo1.jpg"/></a>
        </td>
        
    <td align="right" valign="middle"> <br>
   <!--<a href="front.jsf" rendered="#"> Accueil<</a> -->
          
    <c:choose>
                <c:when test="${empty sessionScope.accountBean}">
                    
                    <h:commandLink action="Sign on">
                        <h:outputText value="Sign on"/>
                    </h:commandLink>   
                </c:when>
                <c:otherwise>
                    <h:commandLink id ="logout" action="#{accountBean.logoutAction}" >
            	        <h:outputText value="log out"/>
                    </h:commandLink>
               </c:otherwise>
            </c:choose>
        </td>
    </tr>
</table>

<table cellspacing="0" width="100%">
    <tr>
        <td>
            <hr color="#99ca3c"  size="5" noShade SIZE=1>
        </td>
    </tr>
</table>
    
	</h:form>
</f:subview>

The accountBean code :

public class AccountBean extends BaseBean{
//private Logger log = Log.getLog(this);
    private String uid;
    private String password;
    
    private boolean loggedIn;
    private AdminService adminService;
    private Admin admin;
    public AccountBean() {
        this.logger.debug("Authentication");
        this.loggedIn = false;
        uid=null;
        password=null;
       // admin=new Admin();
    }
public String loginAction() {
		try {
                    this.logger.debug("loginAction");
                   
                     admin = adminService.login(this.uid, this.password);
                                //this.serviceLocator.getUserService().login(this.username, this.password);
			
			if (admin != null) {
                            if("".equals(admin.getUid())|| "".equals(admin.getPassword())){
                             this.loggedIn=false;
                                String msg = "Le mot de passe et l'identifiant doivent etre saisis ";
				addErrorMessage(msg + ", saississez un mot de passe et un identifiant corrects");
                             return NavigationResults.RETRY;
                            }
                            else{
				this.loggedIn = true;
                                HttpSession session = SessionUtil.getSession();
                                session.setAttribute("Admin", this.uid);
				
				return NavigationResults.SUCCESS;
                            }
			}
			else {
				this.loggedIn = false;
				
				String msg = "Le mot de passe est incorrect ";
				addErrorMessage(msg + ", saississez un mot de passe correct");
				this.logger.debug(msg);
				
				return NavigationResults.RETRY;
			}
		}
		catch (UsernameNotExistException ue) {
			String msg = "L'identifiant (login) est incorrect";
			this.logger.info(msg);
			addErrorMessage(msg + ", ressaysissez votre identifiant.");
			
			return NavigationResults.RETRY;
		}
		catch (Exception e) {
			this.logger.error("Could not log in user.", e);
			addInfoMessage("Could not log in user: Internal Error");
			
			return NavigationResults.FAILURE;
		}
	}
	
	/**
	 * The backing bean action to logout a user.
	 * 
	 * @return the navigation result
	 */
	public String logoutAction() {
		//this.clear();
           FacesContext fc = FacesContext.getCurrentInstance();
           HttpSession session = (HttpSession) fc.getExternalContext().getSession(false);
           session.invalidate();

		this.logger.debug("Logout successfully.");
		
		return NavigationResults.MAIN;
	}
	
   
    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String getUid() {
        return uid;
    }

    public void setUid(String uid) {
        this.uid = uid;
    }

    public Admin getAdmin() {
        return admin;
    }

  
    public boolean getLoggedIn() {
        return loggedIn;
    }

    public void setLoggedIn(boolean loggedIn) {
        this.loggedIn = loggedIn;
    }

    public void setAdminService(AdminService adminService) {
        this.adminService = adminService;
    }
    

}

the faces managed bean configuration

<managed-bean-name>accountBean</managed-bean-name>
    <managed-bean-class>fr.cbmjadmin.views.bean.AccountBean</managed-bean-class>
    <managed-bean-scope>session</managed-bean-scope>
    <managed-property>
	<property-name>adminService</property-name>
            <value>#{adminService}</value>
    </managed-property>

2/ the second problem :
my application shows a list of datas.
I log on the application , i update this list outside the application ( by using sql command) , i try to list my data using the application : the application does not reflect the modifications. I logout using the log out link, then i log on and the application does not reflect the modifications.

what happens?
How could I resove these problems.
How can i logout properly?
how can i show logout link when the user is logged in? and hide the log out link when the user is logout
Thanks.