(CLOSED) - App is not working when placed in root folder

[eluser]gryzzly[/eluser]
Hello,

I have a strange problem that i do not arrive to debug. Let me show you : [links edited]

A] http://store.domain.tld/store/CodeIgniter
B] http://essai.domain.tld


Both A and B represent the same website, they are on the same distant host.

The only differences are

1) subdomains :

Code:

store.domain.tld    points to     /www
essai.domain.tld    points to     /www/store/CodeIgniter

2) $config['base_url']

Code:

if($_SERVER['HTTP_HOST']=='store.domain.tld'){
    $config['base_url'] = "http://".$_SERVER['HTTP_HOST']."/store/CodeIgniter/";
}
elseif($_SERVER['HTTP_HOST']=='essai.domain.tld'){
    $config['base_url'] = "http://".$_SERVER['HTTP_HOST']."/";
}
else{
// ...
}

The A] website functions correctly. All urls load the right page :

Code:

http://store.domain.tld/store/CodeIgniter/                 =>    points to the home
http://store.domain.tld/store/CodeIgniter/contact          =>    points to the contact page
http://store.domain.tld/store/CodeIgniter/legal-mentions   =>    points to the legals
etc, etc...

The B] website does NOT function. The only url that load the right page is the home.

Code:

http://essai.domain.tld/                =>    points to the home : OK
http://essai.domain.tld/contact         =>    points to the home : BAD
http://essai.domain.tld/legal-mentions  =>    points to the home : BAD
etc, etc...

Locally, the website functions perfectly, both from subfolders or from root folder :
- http://localhost/store/CodeIgniter/
- http://store.dev/ (that points on /store/CodeIgniter )

What can be the thing ?
I'm completly lost and do not know where to search.

Thank's for reading, and for future answers !
Emmanuel.