check error on username and email on https

i have ajax register installed on my site. it all worked fine on my sandbox site which is on http. when i moved the site to production and installed ssl (https) the username and email check in the ajax register form gives a check error and will not let a user register ..... all other boxes are fine.
I tried a few things and switching off the asynchronous check on the https site seems to make it work again ....
it s a workaround but you might wan to double check.
jk

Which version of Joomla is it?
Check your configuration.php and make sure the live_site parameter is empty:
public $live_site = '';