error after install joomla /object not found

[tonjaa]

Xampp 1.7.3a / joomla 1.5.15
after i create directory at opt/lampp /htdocs/joomla99 and create new database in phpmyadmin
i install joomla to directory name joomla99 and use localhost/joomla99 for install joomla
but at second step Pre-installation check at > configuration.php Writable it's show No in red
i don't understand and i next to step for install to Finish . when i want to open http://localhost/joomla99/administrator it's show
Object not found!

The requested URL was not found on this server. If you entered the URL manually please check your spelling and try again.
If you think this is a server error, please contact the webmaster (you@example.com).
Error 404

localhost (http://localhost/)
Fri 02 Apr 2010 01:03:39 PM ICT
Apache/2.2.14 (Unix) DAV/2 mod_ssl/2.2.14 OpenSSL/0.9.8l PHP/5.3.1 mod_apreq2-20090110/2.7.1 mod_perl/2.0.4 Perl/v5.10.1

and when i use http://localhost/joomla99 it's show
No configuration file found and no installation code available. Exiting...

how to fix this problem please guide me by step .

[tonjaa]

i can install Joomla . the problem is about permission for write file configuration.php
i try to in stall again after i create new database and build directory i must to change permission of i directory when install for can write configuration.php file.
and i edit function at Pre-installation check on,off for correct and green all at file php.ini
now it's ok.