Redirect after registration and account activation

Hi everybody,

I wonder if there is a solution for custom redirection after user registered himself and after he activates his own account (via email link).

I found this

function __my_registration_redirect(){
    return home_url( '/page-name/' );
}
add_filter( 'registration_redirect', '__my_registration_redirect' );

but it’s not working. It should be placed in the function.php. I put it in the function.php of the main blog, where the register requests are redirected. It doesn? do anything.

Maybe it’s because I have a multisite and this approach is just for single site. I understand that from all sites the registration leads to the main site register form, but I need to user be redirected to the previous site main page after registration (I only need this for one site, so there is no need to remember which site he came from, always the same). Same thing for the account activation.

Thanks for any advice.