session from http to https

[eluser]sampada[/eluser]
Hi,

I want to redirect the user to the previous page which he was referring before login. so I kept the link of previous page in a session variable and redirected to that session after login.
It worked fine in local server. But when I moved the same code to main site then it didn;t work.
I think the main cause is separate domains i.e www and after login they move to secure

I have also set $config['cookie_domain'].

Is there any way to accomplish this?

Thanks