Problem after installing WP 2.6 (wp-blog-header.php)

Please havw a short look at this. Installed whole WP 2.6 in https://www.klikke.no/linselusa folder. Installation went OK, but after logging in first time problems startet – If trying the link above you find this message :

Warning: require() [function.require]: Unable to access ./linselusa/wp-blog-header.php in /home/virtual/klikke.no/public_html/linselusa/index.php on line 17

Warning: require(./linselusa/wp-blog-header.php) [function.require]: failed to open stream: No such file or directory in /home/virtual/klikke.no/public_html/linselusa/index.php on line 17

Fatal error: require() [function.require]: Failed opening required ‘./linselusa/wp-blog-header.php’ (include_path=’.:/usr/local/lib/php’) in /home/virtual/klikke.no/public_html/linselusa/index.php on line 17

Are this a well known error ? I am 100 % sure that the alle WP files, included wp-blog-header.php and index.php are in the https://www.klikke.no/linselusa file. In index.php file I have written :

“/** Loads the WordPress Environment and Template */
require(‘./linselusa/wp-blog-header.php’);”