Custom permalink structure disturbs my jQuery/AJAX function

I am using Custom Post Type Permalinks plugin to set a custom structure for my permalinks using only settings/general in the admin area of WordPress.

The custom permalink structure I am using is :

/%postname%/%product_category%/

In addition, I have under my single-CPT.php page a select tag that triggers some jquery/ajax actions. When I remove the custom permalink structure, which automatically activates the default permalink strucure, everything works like a charm. But after activating the above structure, the DIV that should display results resturned by jquery/ajax,embeds the whole page in a weird manner.

My jquery code is:

$('select.select').change(function(e) {

    e.preventDefault(); 
    var value = $('select.select option:selected').val(); 

    create_ayat_selectCPT(value); // AJAX function


}) 

Thank you very much for your help, I am 2 days digging to find the solution.

Note that I am using cutom post types in my website.

Edit:
Taking into consideration Damon answer, the permalink structure affects the behaviour of the jquery/ajax function. In fact, if I change to /%product_category%/%postname%/, the Ajax call is executed but with no success.

Result: I have actually the alert displaying the error message.

The function jquery/ajax function is :

function create_ayat_selectCPT(str) 
{

            $.ajax({
                    type: "GET",
                    url: "wp-admin/admin-ajax.php",
                    dataType: 'html',
                    data: ({ action: 'createAyatSelectCPT', id: str}),
                    success: function(data){

                    $('#second-select').html(data);

                    },
                    error: function(data)  
                    {  
                    alert("Your browser broke create ayat  cpt select!");
                    return false;
                    }  


                }); //ajax

    return false;
}

Under functions.php:

function createAyatSelectCPT() {

$ca=$_GET['id']; 

?>
<form method="post" action="">  


            <select class="select2" id="selectid"> 

                            <?php

                            $my_query = new WP_Query();

                            $args = array(
                                    'post_type' => 'product',
                                    'tax_query' => array(
                                        array(
                                            'taxonomy' => 'product_category',
                                            'terms' => array($ca) 
                                        )
                                    )
                                );


                            $my_query->query($args);


                            if ($my_query->have_posts()) : while ($my_query->have_posts()) : $my_query->the_post(); 

                               ?>
                                        <option value="<?php the_ID();?>"><?php the_title(); ?></option>
                                <?php

                            endwhile;
                            endif;

            wp_reset_query();
            die();  
?>

</select>
</form>

<?php
}


add_action('wp_ajax_createAyatSelectCPT', 'createAyatSelectCPT');
add_action('wp_ajax_nopriv_createAyatSelectCPT', 'createAyatSelectCPT'); 

The concerned HTML tag to modify is:

<div id="second-select">...</div>

Edit 2 After installing Firebug :

404 Not Found File: http://localehost.com/enc/products/stuff/stuff/wp-admin/admin-ajax.php?action=createAyatSelectCPT&id=132

Then, the problem comes from the location admin-ajax.php. this file doesn’t exist in this location. So the new permalink structure requires that I modify the path to admin-ajax.php in my jquery script file.