I've got a wordpress site, and that i produced a brand new php project under this wordpress site.

wordpress site world wide web.wpp.com,
project home folder world wide web.wpp.com/project/
I've submitted all project files under this folder, Basically go into the address bar www.wpp.com/project/add.php, edit.php or any other files, there's not a problem, the website shows the page content, but when I enter world wide web.wpp.com/project/remove.php, the website is giving nothing found error. I attempted renaming this file to remove.php, a.perl but each time it gives nothing found error. This page's submissions are not too more diverse from add.php and edit.php files.

.htaccess file

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>

# END WordPress

How do i fix this problem?
thanks.