WP login or membership not working in Firefox

I created a new subdomain school.icanapply.com. If I am using Chrome, IE, Firefox on the main site, icanapply.com, and open a new window, I will be logged into the new sub-domain. I can log into the subdomain using Chrome or IE but not Firefox. I am using the Responsive theme on icanapply.com . I have tried to add the site to my approved sites in my preferences but that does not work either. I have tried on another computer but it will not work on the sub-domain using Firefox. It works fine using other themes with the other browsers. I just discovered I am able to sign in on http://school.icanapply.com/account/ through the WP login but not the membership 2 login.