-text_field_with_auto_complete- browser problems

Hello, i'm using the following in my rails app. works like a charm on IE. but on FF no autocomplete popup is displayed. can somebody help?

rails code:   <p>      <%= text_field_with_auto_complete :person, :nachname, {},      {       :select => 'name',       :after_update_element =>         "function(element,value) " +         "{ " +         remote_function(:update=>'Kundendaten',           :url=>{:action=>:update_kundendaten},           :with=>"'adr_id='+value.id") + ";" +         "}"      }      %>   </p>

html result: <p>     <style>       div.auto_complete {               width: 350px;               background: #fff;             }        div.auto_complete ul {               border:1px solid #888;               margin:0;               padding:0;               width:100%;               list-style-type:none;             }       div.auto_complete ul li {               margin:0;               padding:3px;             }       div.auto_complete ul li.selected {               background-color: #ffb;             }       div.auto_complete ul strong.highlight {               color: #800;               margin:0;               padding:0;             } </style>

<input id="person_nachname" name="person[nachname]" size="30" type="text" /> <div class="auto_complete" id="person_nachname_auto_complete"></div>

<script type="text/javascript"> //<![CDATA[ var person_nachname_auto_completer = new Ajax.Autocompleter('person_nachname', 'person_nachname_auto_complete', '/vermietung/auto_complete_for_person_nachname', {afterUpdateElement:function(element,value) { new Ajax.Updater('Kundendaten', '/vermietung/update_kundendaten', {asynchronous:true, evalScripts:true, parameters:'adr_id='+value.id});}, select:'name'}) //]]> </script> </p>