Magento ››› Multi Domain ››› SSL ››› Session Lost

Hi, We're running a multi-domain Magento store with 2 domains, 1.) domainA and domainB 2.) When checkout, we move the customers to domainB with the session in the link. 3.) both domain is running over SSL. (https:// ... ) Everything worked perfectly in 1.8.x , but after upgrading to 1.9.1 the session is lost when redirect the customer to domainB. If the SSL if OFF in domainB - the session is working perfectly... but if SSL is ON, the session is lost in domainB and the cart is 'empty'. Thanks...