I start with the reason. I wanted only my domain to stay in the address bar up in the browser, so I figured it out. I made an index.html frame-set page with 2 frames. The one I called up.html and set it to zero hight and no border, so that it cannot be seen. The other is under the first one and there I run the WP site.
All functions work, even though the WP site is on another server. New peaople can register, but cannot login after that.
When I try to login, no matter if like an admin or an user, I write the name and password corectly and then after pressing the login botton I come to the Login page with no name or password filled.
If I write eather name or password wrong, it says that it's wrong.
I would be thankful for every help.
p.s.: If I try to login through the real path (not in the frame in the frameset-page) I can!
Thanks a lot!