HTTPS and admin-ajax.php conflict

I am using Multisite & SSL with Wordpress HTTPS plugin. I also using a plugin UserPro from Codecanyon. The problem is, when i want to register new blog, this error shows up.

Error in jQuery.ajax while submitting a form:[Exception... "<no message>" nsresult: "0x805e0006 (<unknown>)" location: "JS frame :: https://jomborak.my/main/wp-includes/js/jquery/jquery.js?ver=1.11.1 :: .send :: line 4" data: no]

I try to troubleshoot the problem and I think the problem come from admin-ajax.php which are called from a http protocol. It was trying to fetch data from this link: http://jomborak.my/main/wp-admin/admin-ajax.php. It blocked loading mixed active content (https and http). So how do i make the admin-ajax.php being called over https.

My website URL is jomborak.my
You can try register your own blog there and see the problem yourself. Some browser didnt show up the error message.