[horde] Help needed, login.php not found!

[jasonlee at heavenbridge.com]

Hello everyone, i am new to linux, so i may have a lot of question that
seems really dumb... but i do need help with the configuration of horde in
order to get it to work properly. any help is greatly appreciated.

I've sucesscully installed horde, and imp. i know this because the
test.php works properly and everything shows.
when i goto http://webaddress/horde , the page shows correctly too
but when i tried to log in . it gave me the following error:
Warning: Failed opening 'Log.php' for inclusion
(include_path='.:/usr/local/lib/php') in
/var/www/html/horde/lib/Horde.php on line 145

Fatal error: Undefined class name 'log' in
/var/www/html/horde/lib/Horde.php on line 155

i am not sure what do do.. any help is appreciated.