Custom tabs no longer showing – WooCommerce 2.01

Hi guys, i have some custom tabs and when i updated to woo 2.01 they have been replaced with this error:

Warning: uasort() expects parameter 1 to be array, null given in /home/jayseven/public_html/woo/wp-content/plugins/woocommerce/woocommerce-template.php on line 792

An example of my tab code below:

//---------------------------------------------------------------------------add contact tab

add_action('woocommerce_product_tabs', 'woocommerce_product_installation_tab', 50);
add_action('woocommerce_product_tab_panels', 'woocommerce_product_installation_panel', 50);

if (!function_exists('woocommerce_product_installation_tab')) {
function woocommerce_product_installation_tab( $current_tab ) {
global $_product;
?>
<li <?php if ($current_tab=='#tab-installation') echo 'class="active"'; ?>><a href="#tab-installation"><?php _e('Contact', 'woocommerce'); ?></a></li>
<?php
}
}   

if (!function_exists('woocommerce_product_installation_panel')) {
function woocommerce_product_installation_panel() {

global $_product;

echo '<div class="panel" id="tab-installation">';
echo '<h2>' . apply_filters('woocommerce_product_installation_heading', __('Contact', 'woocommerce')) . '</h2>';
echo '<h4> Contact us about ' . apply_filters( 'woocommerce_single_product_title', the_title( '', '', false ) ) . '</h4>';
gravity_form(1, false, false, true, false, true);
 echo '</div>';

}
}

Hopefully a simple fix, but urgently required!

Thanks.

https://www.ads-software.com/extend/plugins/woocommerce/