Ane kan mau masukin script datepicker di web ane gan, tapi setelah ane masukin kenapa javascript bawaan templatenya jadi gak berfunsi?

<meta http-equiv="content-type" content="text/html; charset=utf-8" />

<link rel="stylesheet" media="screen,projection" type="text/css" href="css/reset.css" />

<link rel="stylesheet" media="screen,projection" type="text/css" href="css/main.css" />

<link rel="stylesheet" media="screen,projection" type="text/css" href="css/2col.css" title="2col" />

<link rel="alternate stylesheet" media="screen,projection" type="text/css" href="css/1col.css" title="1col" />

<!--[if lte IE 6]><link rel="stylesheet" media="screen,projection" type="text/css" href="css/main-ie6.css" /><![endif]-->

<link rel="stylesheet" media="screen,projection" type="text/css" href="css/style.css" />

<link rel="stylesheet" media="screen,projection" type="text/css" href="css/mystyle.css" />

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 $(document).ready(function(){

 $(".tabs > ul").tabs();

 });

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<!-- Date Picker -->

 <link type="text/css" href="js/datepicker/themes/ui-lightness/ui.all.css" rel="stylesheet" /> 

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 $(document).ready(function(){

 $("#date_post").datepicker({

 dateFormat : "dd/mm/yy", 

 changeMonth : true,

 changeYear : true 

 }); 

 });

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<!-- Date Picker End -->

Script diatas datepicker itu itu jquery tab gan, datepickernya normal, tabnya jadi gak berfungsi, alhasil web ane berantakan, klo dibalik datepicker yg jadi gak berfungsi, jadi kyak saling nimpa gitu. Apa ada cara buat kombinasiin scriptnya ya, secara untuk js ane newbie..