exec and system do not work

Dear List -

I'm lost on this one -

This works -

$out = system("ls -l ",$retvals);
printf("%s", $out);

This does -

echo exec("ls -l");

This does not -

if( !file_exists("/var/www/orders.txt"));
{
    $out = system("touch /var/www/orders.txt", $ret);
    $out2 = system("chmod 766 /var/www/orders.txt", $ret);
    echo 'file2<br />';
    echo file_exists("/var/www/orders.txt");
}

and this does not -

if( !file_exists("/var/www/orders.txt"));
{
    exec("touch /var/www/orders.txt");
    exec("chmod 766 /var/www/orders.txt");
    echo 'file2<br />';
    echo file_exists("/var/www/orders.txt");
}

Ethan