mount / and / or apache - php permissions : where should I look?

Here's the configuration :

The directory :

/var/www/mount_ImpExp/ImpExp/

is a shared directory (Linux) from a PC with an IP adress 192.168.1.12

My PC IP adress is 192.168.1.11

I mounted that shared dir with the command : mount -t cifs -o auto,username=myusername,password=mypass //192.168.0.12/LINUX_U /var/www/mount_ImpExp

If I try to manually launch a rsync with :

rsync -t /var/www/mount_ImpExp/ImpExp/compteur_assur /usr/bin/

This works :

ls -al /usr/bin/compteur_assur
-rwxr-xr-x 1 zobz zobz 2501 2009-06-09 15:44 /usr/bin/compteur_assur

Now I create a exec.php file in my website : the path is : /var/www/html/Internet/mywebsite

the source is :

echo date('d/m/Y H:i:s');
echo "<br />";
var_dump(
  system("rsync -t /var/www/mount_ImpExp/ImpExp/compteur_assur /usr/bin/"));

it doesn't work.

In the php.ini the "safemode" is "off". So I may be able to execute any shell command. If I try to modify the exec.php file and do a simple :

var_dump( system("ls -al ."));

It works. So the "system" call works.

Thus I tried to modify the options in the httpd.conf file :

    # Ajout Olivier Pons / 11 juin 2009
    <Directory "/var/www/mount_ImpExp/ImpExp">
        AddDefaultCharset UTF-8
        Options All
        AllowOverride All
        Order allow,deny
        Allow from all
    </Directory>

I then restarted the server and nothing works. What shall I do where should I look next ? I'm stuck...