Programmatic login doesn't work with subDomains ?

Question

greetings all i am using the following method to make an auto login for user after registration to access an authenticated page:

public static void autoLogin(User user, HttpServletRequest request,
            AuthenticationManager authenticationManager) {

        GrantedAuthority[] grantedAuthorities = new GrantedAuthority[] { new GrantedAuthorityImpl(
                user.getAuthority()) };

        UsernamePasswordAuthenticationToken token = new UsernamePasswordAuthenticationToken(
                user.getEmail(), user.getPasswordBeforeHashing(),
                grantedAuthorities);

        // generate session if one doesn't exist
        request.getSession();

        token.setDetails(new WebAuthenticationDetails(request));
        Authentication authenticatedUser = authenticationManager
                .authenticate(token);

        SecurityContextHolder.getContext().setAuthentication(authenticatedUser);
        // setting role to the session
        request
                .getSession()
                .setAttribute(
                        HttpSessionSecurityContextRepository.SPRING_SECURITY_CONTEXT_KEY,
                        SecurityContextHolder.getContext());

    }

note: registration page have the rule that no filters are applied on it in security.xml file.

after the auto login i redirect the user to an authenticated page something like

http://www.appName.come/page

it works fine with such behaviour

but when i try to redirect the user to the same page under a subDomain,something like

http://www.x.appName.come/page (we have the rule in apache that *.appName is the same like appName)

it doesn't go the page and considers the user un-authenticated and redirects him to the login page, any ideas why such behaviour occurs ?