[imp] login problem through IMP

[Roman Gavrilov]

I have horde 3.0 and imp 4.0 installed.
I set horde to do authentication through IMP.

uncommented next lines:
$conf['auth']['driver'] = 'application';
$conf['auth']['params']['app'] = 'imp';

now when I am trying to login I get blank page domain/horde/img/redirect.php.
if I hit on reload it will then reload the page with the welcome page without the left menu.
I need to delete the whole part of imp from the url address to get to horde main page with frames (domain/horde/).
It worked ok when horde did the authentication by it self.

What should I do so when imp done with authentication it will redirect me to horde main page (index.php) ?
Thanks