[jQuery] toggle function failed in tomcat

[jQuery] toggle function failed in tomcat


when i use this address file:///D:/apache-tomcat-6.0.18/webapps/tree/tree.html
it works.
when i use http://localhost:8080/tree/tree.html
it failed.
why ? could you help me? THANK YOU!
HTML:
<ul class="root" id="0">
    <img id="img1" src="img/plus.gif" /><img src="img/folder.gif"/>
</ul>
custom3.js
$(document).ready(function(){
$(".root").toggle(function(){
$("#"+this.id+" > img:first").attr("src","img/minus.gif");
},function(){
$("#"+this.id+" > img:first").attr("src","img/plus.gif");
});
    });