[Moo] spinner do not shows up on Request.HTML

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Hello,
i have a problem with moo-spinner. It doesn't show up.
i am using:
mootools-1.2.3-core-nc.js and mootools-1.2.3.1-more.js

my js:

$('login_text').set('text','Register');  //works fine
                  new Request.HTML ({
                    url: baseurl + 'js/login/signup.php',
                    spinnerTarget: $('login_text'),
                    useSpinner: true,
                    spinnerOptions: {
                        message: "please wait ..."
                    },
                    method: 'post',
                    update: $('orgPannel_left'),
                    onComplete: function() {
                        $
('orgPannel_left').highlight('#fff','#6D84B4');
                    }
                  }).post($('registerForm_'));


my css:
.spinner {  position: absolute; opacity: 0.9;   filter:
alpha(opacity=90);  z-index: 999;}
.spinner-msg {  text-align: center; font-weight: bold; color:green;}
.spinner-img {
background:#6D84B4 url(images/facebox_indicator.gif) no-repeat;width:
24px;height: 24px;margin: 0 auto;}


Any Idea whats wrong here?