Creating a input mask for postcode

[grlongo]

Hi mates.

 

I am using oscommerce v2.3

 

I´m trying to create a mask to the field Postcode in create_account form.

 

So, the method I´m using is:

 

I set in /include/template_top.php

<script type="text/javascript" src="ext/jquery/masks.js"></script>

 

then ... in ext/jquery/masks.js

 

$(document).ready(function(){  
$(function(){  
$.mask.addPlaceholder("~","[+-]");  
$("#postcode").mask("99999-999");  
});  
});  

 

the code in the create_account form is like this:

<tr>
<td class="fieldValue"><input type="text" name="postcode" id="postcode"> <span class="inputRequirement">*</span></td>
<input type="text" name="postcode" id="postcode">
<span class="inputRequirement">*</span>
<td class="fieldValue"><input type="text" name="postcode" id="postcode"> <span class="inputRequirement">*</span></td>
</tr>

 

Am I doing something wrong??? Please, could I get some help from here cause I can´t make this work.

Thanks