Symfony 2 Configuration of directories

Symfony 2 Configuration of directories

I found some topics with similar problem, but I've never been able to fix
mine.
I've just started Symfony2 development. I work with MAMP. Before, my
project directory path was this path :
/Applications/MAMP/htdocs/TrainingProject/Symfony/
And my configuration on MAMP for "Document root" was :
/Applications/MAMP/htdocs/TrainingProject/Symfony/web/
With this paths, I can launch app_dev.php and app.php without problems.
I wanted to created a subfolder inside TrainingProject to organize couple
stuff... So I wanted to have this new path for my project :
/Applications/MAMP/htdocs/TrainingProject/THE_SUBFOLDER/Symfony/
So I've edit the Document root on MAMP settings :
/Applications/MAMP/htdocs/TrainingProject/THE_SUBFOLDER/Symfony/web/
After my changes, I have a really weird behavior!
http://localhost:8888/config.php works
http://localhost:8888/app_dev.php works
http://localhost:8888/ DOESN'T WORK !! ...
http://localhost:8888/app.php DOESN'T WORK !! ...
Another problem, for writing cache, it writes always on the old path. So
It creates a folder Symfony inside TrainingProject, with his subfolders
just for the CACHE...
With my previous architecture, everything worked!
I've already tried to empty the cache with this command :
php app/console cache:clear --env=prod --no-debug
Nothing changed...
Help please