So you can log in from the www.MainWebSite.com* however* when you try to log in from any of the other websites* it loads and looks like everything works* but then it bombs out* and it's as if you never logged in at all.
So why can you log in to the Main Website* but any forwarded one will not log in? Again* the forward works because you can see the site* you just can't log in from those websites.