Ultimate SEO URLs: fatal error

[X@vier]

Hello,

I installed (or tried to) the Ultimate SEO URLs on www.mindex.be/anatest
It seems to work on the site itself.

But when I want to access the admin pages I get the follwoing error message:

Warning:  zen_href_link(includes/classes/seo.url.php): failed to open stream: No such file or directory in /home/anamorf/public_html/anatest/admin/includes/functions/html_output.php on line 18

Warning: zen_href_link(): Failed opening 'includes/classes/seo.url.php' for inclusion (include_path='.:/usr/lib/php:/usr/local/lib/php') in /home/anamorf/public_html/anatest/admin/includes/functions/html_output.php on line 18

Fatal error:  Cannot instantiate non-existent class:  seo_url in /home/anamorf/public_html/anatest/admin/includes/functions/html_output.php on line 20 

What have I done wrong?

Thank you for helping me.

Xavier