Add mutilpe image gallery custom drupal 7 with ajax

 /Implementing the hook menu//

 function gallery_menu() {
    $items = array();
    $items['gallerysadd'] = array(
        'title' => 'Test Module WWC',
        'page callback' => 'wwc_test_gallery',
        'access callback' => 'user_access',
        'access arguments' => array('access content'),
    );
    return $items;

}


//calling the  drupal form

function wwc_test_gallery(){
    return(drupal_get_form('upload_Gallery_form'));
    }


//custome  the form

function upload_Gallery_form($form, &$form_state){
    
$form['private_gallery'] = array(
        '#prefix' => '<div id="privategallery-fieldset-wrapper">',
        '#suffix' => '</div>',
        '#type' => 'fieldset',
        '#title' => t('Gallery'),
    );

    if (empty($form_state['num_private_gallery'])) {
        $form_state['num_private_gallery'] = 1;
    }

    for ($i = 0; $i < $form_state['num_private_gallery']; $i ++) {
        $form['private_gallery']['privategallery' . $i] = array(
            '#name' => 'files[privategallery' . $i . ']',
            '#type' => 'managed_file',
            '#title' => t(''),
            '#upload_location' => 'public://cruisetemplates/',
            '#default_value' => $privategalleryArray[$i]
        );
    }

    $form['private_gallery']['privateevent_addgallery'] = array(
        '#name' => 'private_gallery',
        '#type' => 'submit',
        '#value' => t('Add one more Gallery'),
        '#submit' => array('ajax_add_private_gallery_submit'),
        '#ajax' => array(
            'callback' => 'ajax_add_private_gallery_callback',
            'wrapper' => 'privategallery-fieldset-wrapper'
        )
    );

        return $form;   
}
//calling the  ajax function when ajax and retun the  form
function ajax_add_private_gallery_callback($form, $form_state) {
    return $form['private_gallery'];
}
//submit rebuit the  form
function ajax_add_private_gallery_submit($form, &$form_state) {
    $form_state['num_private_gallery'] ++;
    $form_state['rebuild'] = TRUE;
}