I want to reproduce this simply behaviour :

http://tinymcesupport.com/tutorials/autoresize-automatic-resize-plugin

This is my init:

<!-- TinyMCE -->
    <script type="text/javascript" src="js/jscripts/tiny_mce/tiny_mce.js"></script>
    <script type="text/javascript">
        tinyMCE.init({
            mode : "exact",
            elements : "pagina_testo_colonna1,pagina_testo_colonna2,pagina_testo_colonna3",
            theme : "advanced",
            plugins:"paste,autoresize",
            plugin_preview_width : "100%",
            width : "100%",
            theme_advanced_buttons1 : "pastetext,|,bold,italic,underline,strikethrough,|,bullist,numlist,|,indent,outdent,|,undo,redo,|,justifyleft,justifycenter,justifyright,justifyfull,|,link,unlink,|,charmap",
            theme_advanced_buttons2 : "",
            theme_advanced_buttons3 :"",
            theme_advanced_disable : "image,anchor,cleanup,help,code,hr,removeformat,sub,sup",
            theme_advanced_resizing : true,
            paste_text_use_dialog : true,
            relative_urls : false,
            remove_script_host : false

        });
    </script>
    <!-- /TinyMCE -->

i have added "autoresize" to plugins list but my editors not resize while i writing, they simply scroll. I have multiple editor in the same page. What's wrong with my code?