Problem in creating tab using JQuery EasyUI

Question

Hi

i have created tab using JQuery EasyUI

i am writing code which is working correct but the problem is that when i implement same functionality in my other files there i got a error.

the error is

" Uncaught TypeError: $(...).tabs is not a function"

if anyone know why this error is coming kindly help me.

CSS & JS

<link rel="stylesheet" type="text/css" href="http://www.jeasyui.com/easyui/themes/default/easyui.css">

<link rel="stylesheet" type="text/css" href="http://www.jeasyui.com/easyui/themes/icon.css">

<script type="text/javascript" src="http://code.jquery.com/jquery-1.4.4.min.js"></script>

<script type="text/javascript" src="http://www.jeasyui.com/easyui/jquery.easyui.min.js"></script>

This is code HTML

<div style="margin-bottom:10px">

<a href="javascript: void(0);" class="easyui-linkbutton" onclick="addTab('google','http://www.google.com')">google</a>

<a href="javascript: void(0);" class="easyui-linkbutton" onclick="addTab('jquery','http://jquery.com/')">jquery</a>

<a href="javascript: void(0);" class="easyui-linkbutton" onclick="addTab('easyui','http://jeasyui.com/')">easyui</a>

<a href="javascript: void(0);" class="easyui-linkbutton" onclick="addTab('google','http://www.google.com')">google</a>

</div>

<div id="tt" class="easyui-tabs" style="width:400px;height:250px;">

<div title="Home">

</div>

</div>

This is Code of JS

function addTab(title, url){

if ($('#tt').tabs('exists', title)){

$('#tt').tabs('select', title);

} else {

var content = '<div style="width:100%;height:100%;"><h2>'+url+'</h2</div>';

$('#tt').tabs('add',{

title:title,

content:content,

closable:true

});

}

}