[jQuery] just in Firefox 3.0.8 $ is not defined

[Asinox]

Hi, i dont know what happen but just in FF, Jquery show error

error:

$ is not defined


my code:

<script type="text/javascript">
$(document).ready(function(){
         $('#demoOne').listnav();
});
</script>

yes, i have the url to the jquery and the plugin in nice place, but
idont know why just Firefox