I opened a ticket on this two days ago, but not had a reply yet so posting here in the hope somebody can help!
I'm getting the following error on checkout...
Warning: call_user_func_array() [function.call-user-func-array]: First argument is expected to be a valid callback, 'ShareYourCartWooCommerceEx::showCheckoutButton' was given in /home/bedsofpa/public_html/wp-includes/plugin.php on line 406
Am running WooCommerce v. 2.0.5 on WP 3.5.1.
I have tried deactivating all plugins except woocommerce.