CodeIgniter problem after upload to hosting

@php_rocs

a have it in folder and now it's working but i don't know how, I added a line in .htacces:

RewriteBase /folderWithCI/

and in config:

$config['base_url'] = 'http://domain.pl/folderWithCI/';

Don't know why it's not working without that line in htaccess if i have subfolder declarated in baseurl