installation Fatal Error

Hi,
I downloaded WordPress, changed the wp-config.php file and uploaded it into a directory called blog. I even reinstalled everything.
When I run install.php the following appears:

Warning: require_once(../wp-includes/functions.php) [function.require-once]: failed to open stream: No such file or directory in /home/virtual/site206/fst/var/www/html/blog/wp-admin/install.php on line 4

Fatal error: require_once() [function.require]: Failed opening required ‘../wp-includes/functions.php’ (include_path=’.:/php/includes:/usr/share/php’) in /home/virtual/site206/fst/var/www/html/blog/wp-admin/install.php on line 4

my web site: http://www.jabadlaplata.org.ar
blog install dir: http://www.jabadlaplata.org.ar/blog

Please help!