Wrong redirect after logging in via Domain Mapping.

At the front end Domain Mapping works great: sub.domain.com is redirected to http://www.mappeddomain.com, but when I try to log in, it doesn't work.

I enter the correct credentials at http://www.mappeddomain.com, get a windows saying: "You have logged in successfully. You will be redirected to desired page during next 5 seconds." and then it loads http://www.domain.com/wp-admin/user/ saying: "You must log in to access the admin area."

I think I've tried all the settings (except the right one apparently) by now...

What I want is my users to log in via http://www.mappeddomain.com, go to their Dashboard and still keep http://www.mappeddomain.com in their URL. When I log in as SuperAdmin, I'll use http://www.domain.com and want to be able to move through the blogs without logging in over and over. :wink:

What are the correct settings for that, please?