textStatus:error errorThrown:undefined responseText

Hello Bernard,

I’ve answered someone on our support site who was having the same problem.
I believe this is linked to your theme which redirects the non logged in users when they are sending requests to the wp-admin/admin-ajax.php file.

Here is a similar issue, check it out: http://ww.wp.xz.cn/support/topic/theme-redirects-ajax-requests-for-users-that-are-not-logged-in

Cheers,
Ben