Issue with wp-admin https://

Hello,

for security reason when people log in i like to use https:// connection,

I added the following to wp-config.php:
define('FORCE_SSL_ADMIN', true);

This makes my site standard http but the admin pages are https as expected

HOWEVER. even though i am logged in I get

This has been disabled

The ONLY way to make it work is keep peoples passwords etc on unsecured connection

how do I allow it to work on https:// (I’d rather have the disabled message for the http version)

NOTE: Even when i edit the wp-config.php back to stop the https redirection on admin pages, it still blocks me if i add https to any of the login or admin pages – how do i fix this as people tend to enter passwords a lot less on sites not secured, and no point making the WHOLE site https/ssl when the only part i need is wp-admin and the /login/ page!

is there any way to do this? (for now ive had to turn off the plugin.. already had bots attacking it 14 times in just under 5 mins trying to recreate accounts or hack into the “admin” (which is not even an account as i changed it on install)

thanks